- 11 Apr, 2016 6 commits
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Vitaly Kuznetsov authored
commit e513229b upstream. When an SMP Hyper-V guest is running on top of 2012R2 Server and secondary cpus are sent offline (with echo 0 > /sys/devices/system/cpu/cpu$cpu/online) the system freeze is observed. This happens due to the fact that on newer hypervisors (Win8, WS2012R2, ...) vmbus channel handlers are distributed across all cpus (see init_vp_index() function in drivers/hv/channel_mgmt.c) and on cpu offlining nobody reassigns them to CPU0. Prevent cpu offlining when vmbus is loaded until the issue is fixed host-side. This patch also disables hibernation but it is OK as it is also broken (MCE error is hit on resume). Suspend still works. Tested with WS2008R2 and WS2012R2. Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
K. Y. Srinivasan <kys@microsoft.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Chas Williams <3chas3@gmail.com> [ luis: backported to 3.16: adjusted context ] Signed-off-by:
Luis Henriques <luis.henriques@canonical.com>
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Nicolai Hähnle authored
commit f6ff4f67 upstream. An arbitrary amount of time can pass between spin_unlock and radeon_fence_wait_any, so we need to ensure that nobody frees the fences from under us. Based on the analogous fix for amdgpu. Signed-off-by:
Nicolai Hähnle <nicolai.haehnle@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> (v1 + fix) Tested-by:
Lutz Euler <lutz.euler@freenet.de> [ nicolai: Backport of upstream commit f6ff4f67, with an additional NULL pointer guard that is required for kernels 3.17 and older. To be precise, any kernel that does *not* have commit 954605ca "drm/radeon: use common fence implementation for fences, v4" requires this additional NULL pointer guard.] Signed-off-by:
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Spencer E. Olson authored
commit 1fd24a47 upstream. This fixes a bug in function ni_tio_input_inttrig(). The trigger number should be compared to cmd->start_arg, not cmd->start_src. Fixes: 6a760394 ("staging: comedi: ni_tiocmd: clarify the cmd->start_arg validation and use") Signed-off-by:
Spencer E. Olson <olsonse@umich.edu> Reviewed-by:
Ian Abbott <abbotti@mev.co.uk> Signed-off-by:
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Andy Lutomirski authored
commit b7a58459 upstream. On Xen PV, regs->flags doesn't reliably reflect IOPL and the exit-to-userspace code doesn't change IOPL. We need to context switch it manually. I'm doing this without going through paravirt because this is specific to Xen PV. After the dust settles, we can merge this with the 32-bit code, tidy up the iopl syscall implementation, and remove the set_iopl pvop entirely. Fixes XSA-171. Reviewewd-by:
Jan Beulich <JBeulich@suse.com> Signed-off-by:
Andy Lutomirski <luto@kernel.org> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/693c3bd7aeb4d3c27c92c622b7d0f554a458173c.1458162709.git.luto@kernel.orgSigned-off-by:
Ingo Molnar <mingo@kernel.org> [ kamal: backport to 3.19-stable: no X86_FEATURE_XENPV so just call xen_pv_domain() directly ] Acked-by:
Kamal Mostafa <kamal@canonical.com> Signed-off-by:
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Ingo Molnar authored
commit 590ee7db upstream. Now that we are using smpboot_thread_init() in init/main.c as well, provide it for !CONFIG_SMP as well. This addresses a !CONFIG_SMP build failure. Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by:
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Yan, Zheng authored
commit 1f041a89 upstream. struct timespec uses 'long' to present second and nanosecond. 'long' is 64 bits on 64bits machine. ceph MDS expects time stamp to be encoded as struct ceph_timespec, which uses 'u32' to present second and nanosecond. Signed-off-by:
Yan, Zheng <zyan@redhat.com> BugLink: http://tracker.ceph.com/issues/15302 BugLink: http://bugs.launchpad.net/bugs/1564950 [ kamal: backport to 3.16-stable: no time stamp in __prepare_send_request() ] Signed-off-by:
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- 30 Mar, 2016 5 commits
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Oliver Neukum authored
commit 8835ba4a upstream. An attack has become available which pretends to be a quirky device circumventing normal sanity checks and crashes the kernel by an insufficient number of interfaces. This patch adds a check to the code path for quirky devices. Signed-off-by:
Oliver Neukum <ONeukum@suse.com> Signed-off-by:
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Vladis Dronov authored
commit 950336ba upstream. The ati_remote2 driver expects at least two interfaces with one endpoint each. If given malicious descriptor that specify one interface or no endpoints, it will crash in the probe function. Ensure there is at least two interfaces and one endpoint for each interface before using it. The full disclosure: http://seclists.org/bugtraq/2016/Mar/90Reported-by:
Ralf Spenneberg <ralf@spenneberg.net> Signed-off-by:
Vladis Dronov <vdronov@redhat.com> Signed-off-by:
Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Moritz Muehlenhoff <jmm@inutil.org> Signed-off-by:
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Gabriel Krisman Bertazi authored
commit 21b81716 upstream. Commit d63c7dd5 ("ipr: Fix out-of-bounds null overwrite") removed the end of line handling when storing the update_fw sysfs attribute. This changed the userpace API because it started refusing writes terminated by a line feed, which broke the update tools we already have. This patch re-adds that handling, so both a write terminated by a line feed or not can make it through with the update. Fixes: d63c7dd5 ("ipr: Fix out-of-bounds null overwrite") Signed-off-by:
Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> Cc: Insu Yun <wuninsu@gmail.com> Acked-by:
Brian King <brking@linux.vnet.ibm.com> Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by:
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Insu Yun authored
commit d63c7dd5 upstream. Return value of snprintf is not bound by size value, 2nd argument. (https://www.kernel.org/doc/htmldocs/kernel-api/API-snprintf.html). Return value is number of printed chars, can be larger than 2nd argument. Therefore, it can write null byte out of bounds ofbuffer. Since snprintf puts null, it does not need to put additional null byte. Signed-off-by:
Insu Yun <wuninsu@gmail.com> Reviewed-by:
Shane Seymour <shane.seymour@hpe.com> Signed-off-by:
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Paul E. McKenney authored
commit 00df35f9 upstream. Currently, smpboot_unpark_threads() is invoked before the incoming CPU has been added to the scheduler's runqueue structures. This might potentially cause the unparked kthread to run on the wrong CPU, since the correct CPU isn't fully set up yet. That causes a sporadic, hard to debug boot crash triggering on some systems, reported by Borislav Petkov, and bisected down to: 2a442c9c ("x86: Use common outgoing-CPU-notification code") This patch places smpboot_unpark_threads() in a CPU hotplug notifier with priority set so that these kthreads are unparked just after the CPU has been added to the runqueues. Reported-and-tested-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by:
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- 29 Mar, 2016 7 commits
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Vasily Kulikov authored
commit 8a5e5e02 upstream. Poison pointer values should be small enough to find a room in non-mmap'able/hardly-mmap'able space. E.g. on x86 "poison pointer space" is located starting from 0x0. Given unprivileged users cannot mmap anything below mmap_min_addr, it should be safe to use poison pointers lower than mmap_min_addr. The current poison pointer values of LIST_POISON{1,2} might be too big for mmap_min_addr values equal or less than 1 MB (common case, e.g. Ubuntu uses only 0x10000). There is little point to use such a big value given the "poison pointer space" below 1 MB is not yet exhausted. Changing it to a smaller value solves the problem for small mmap_min_addr setups. The values are suggested by Solar Designer: http://www.openwall.com/lists/oss-security/2015/05/02/6Signed-off-by:
Vasily Kulikov <segoon@openwall.com> Cc: Solar Designer <solar@openwall.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Cc: Moritz Muehlenhoff <jmm@inutil.org> Signed-off-by:
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Takashi Iwai authored
commit 447d6275 upstream. Add some sanity check codes before actually accessing the endpoint via get_endpoint() in order to avoid the invalid access through a malformed USB descriptor. Mostly just checking bNumEndpoints, but in one place (snd_microii_spdif_default_get()), the validity of iface and altsetting index is checked as well. Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=971125Signed-off-by:
Takashi Iwai <tiwai@suse.de> Cc: Moritz Muehlenhoff <jmm@inutil.org> [ luis: backported to 3.16: adjusted context ] Signed-off-by:
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Takashi Iwai authored
commit 0f886ca1 upstream. create_fixed_stream_quirk() may cause a NULL-pointer dereference by accessing the non-existing endpoint when a USB device with a malformed USB descriptor is used. This patch avoids it simply by adding a sanity check of bNumEndpoints before the accesses. Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=971125Signed-off-by:
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Josh Boyer authored
commit 4ec0ef3a upstream. The iowarrior driver expects at least one valid endpoint. If given malicious descriptors that specify 0 for the number of endpoints, it will crash in the probe function. Ensure there is at least one endpoint on the interface before using it. The full report of this issue can be found here: http://seclists.org/bugtraq/2016/Mar/87Reported-by:
Josh Boyer <jwboyer@fedoraproject.org> Signed-off-by:
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Josh Boyer authored
commit 9c6ba456 upstream. The powermate driver expects at least one valid USB endpoint in its probe function. If given malicious descriptors that specify 0 for the number of endpoints, it will crash. Validate the number of endpoints on the interface before using them. The full report for this issue can be found here: http://seclists.org/bugtraq/2016/Mar/85Reported-by:
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David S. Miller authored
commit fbd40ea0 upstream. When an inetdev is destroyed, every address assigned to the interface is removed. And in this scenerio we do two pointless things which can be very expensive if the number of assigned interfaces is large: 1) Address promotion. We are deleting all addresses, so there is no point in doing this. 2) A full nf conntrack table purge for every address. We only need to do this once, as is already caught by the existing masq_dev_notifier so masq_inet_event() can skip this. Reported-by:
Solar Designer <solar@openwall.com> Signed-off-by:
David S. Miller <davem@davemloft.net> Tested-by:
Cyrill Gorcunov <gorcunov@openvz.org> Cc: Moritz Muehlenhoff <jmm@inutil.org> [ luis: backported to 3.16: - file rename: nf_nat_masquerade_ipv4.c -> ipt_MASQUERADE.c ] Signed-off-by:
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Luis Henriques authored
Signed-off-by:
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- 24 Mar, 2016 22 commits
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Steven Rostedt (Red Hat) authored
commit dc17147d upstream. Commit f3775549 ("tracepoints: Do not trace when cpu is offline") added a check to make sure that tracepoints only get called when the cpu is online, as it uses rcu_read_lock_sched() for protection. Commit 3a630178 ("tracing: generate RCU warnings even when tracepoints are disabled") added lockdep checks (including rcu checks) for events that are not enabled to catch possible RCU issues that would only be triggered if a trace event was enabled. Commit f3775549 only stopped the warnings when the trace event was enabled but did not prevent warnings if the trace event was called when disabled. To fix this, the cpu online check is moved to where the condition is added to the trace event. This will place the cpu online check in all places that it may be used now and in the future. Fixes: f3775549 ("tracepoints: Do not trace when cpu is offline") Fixes: 3a630178 ("tracing: generate RCU warnings even when tracepoints are disabled") Reported-by:
Sudeep Holla <sudeep.holla@arm.com> Tested-by:
Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
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Jason Andryuk authored
commit a6807590 upstream. The comparisons should be >= since 0x800 and 0x80 require an additional bit to store. For the 3 byte case, the existing shift would drop off 2 more bits than intended. For the 2 byte case, there should be 5 bits bits in byte 1, and 6 bits in byte 2. Signed-off-by:
Jason Andryuk <jandryuk@gmail.com> Reviewed-by:
Laszlo Ersek <lersek@redhat.com> Cc: Peter Jones <pjones@redhat.com> Cc: Matthew Garrett <mjg59@coreos.com> Cc: "Lee, Chun-Yi" <jlee@suse.com> Signed-off-by:
Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by:
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Matt Fleming authored
commit e246eb56 upstream. Laszlo explains why this is a good idea, 'This is because the pstore filesystem can be backed by UEFI variables, and (for example) a crash might dump the last kilobytes of the dmesg into a number of pstore entries, each entry backed by a separate UEFI variable in the above GUID namespace, and with a variable name according to the above pattern. Please see "drivers/firmware/efi/efi-pstore.c". While this patch series will not prevent the user from deleting those UEFI variables via the pstore filesystem (i.e., deleting a pstore fs entry will continue to delete the backing UEFI variable), I think it would be nice to preserve the possibility for the sysadmin to delete Linux-created UEFI variables that carry portions of the crash log, *without* having to mount the pstore filesystem.' There's also no chance of causing machines to become bricked by deleting these variables, which is the whole purpose of excluding things from the whitelist. Use the LINUX_EFI_CRASH_GUID guid and a wildcard '*' for the match so that we don't have to update the string in the future if new variable name formats are created for crash dump variables. Reported-by:
Peter Jones <pjones@redhat.com> Tested-by:
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Peter Jones authored
commit ed8b0de5 upstream. "rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by:
Lee, Chun-Yi <jlee@suse.com> Acked-by:
Matthew Garrett <mjg59@coreos.com> Signed-off-by:
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Peter Jones authored
commit 8282f5d9 upstream. All the variables in this list so far are defined to be in the global namespace in the UEFI spec, so this just further ensures we're validating the variables we think we are. Including the guid for entries will become more important in future patches when we decide whether or not to allow deletion of variables based on presence in this list. Signed-off-by:
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Peter Jones authored
commit 3dcb1f55 upstream. Actually translate from ucs2 to utf8 before doing the test, and then test against our other utf8 data, instead of fudging it. Signed-off-by:
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Peter Jones authored
commit e0d64e6a upstream. Translate EFI's UCS-2 variable names to UTF-8 instead of just assuming all variable names fit in ASCII. Signed-off-by:
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Peter Jones authored
commit 73500267 upstream. This adds ucs2_utf8size(), which tells us how big our ucs2 string is in bytes, and ucs2_as_utf8, which translates from ucs2 to utf8.. Signed-off-by:
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Marcelo Tosatti authored
commit 7cae2bed upstream. As reported at https://bugs.launchpad.net/qemu/+bug/1494350, it is possible to have vcpu->arch.st.last_steal initialized from a thread other than vcpu thread, say the iothread, via KVM_SET_MSRS. Which can cause an overflow later (when subtracting from vcpu threads sched_info.run_delay). To avoid that, move steal time accumulation to vcpu entry time, before copying steal time data to guest. Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com> Reviewed-by:
David Matlack <dmatlack@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Cc: Liang Chen <liangchen.linux@gmail.com> Signed-off-by:
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Jianjian Huo authored
commit 789d21db upstream. Since bch_is_open will iterate linked list bch_cache_sets and uncached_devices, it needs bch_register_lock. Signed-off-by:
Jianjian Huo <samuel.huo@gmail.com> Cc: Kamal Mostafa <kamal@canonical.com> [ luis: backported to 3.16: adjusted context ] Signed-off-by:
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Greg Kroah-Hartman authored
In Linus's tree, the iovec code has been reworked massively, but in older kernels the AIO layer should be checking this before passing the request on to other layers. Many thanks to Ben Hawkes of Google Project Zero for pointing out the issue. Reported-by:
Ben Hawkes <hawkes@google.com> Acked-by:
Benjamin LaHaise <bcrl@kvack.org> Tested-by:
Willy Tarreau <w@1wt.eu> Signed-off-by:
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Vladis Dronov authored
commit 8e20cf2b upstream. The aiptek driver crashes in aiptek_probe() when a specially crafted USB device without endpoints is detected. This fix adds a check that the device has proper configuration expected by the driver. Also an error return value is changed to more matching one in one of the error paths. Reported-by:
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Eryu Guan authored
commit 6ffe77ba upstream. In commit bcff2488 ("ext4: don't read blocks from disk after extents being swapped") bh is not updated correctly in the for loop and wrong data has been written to disk. generic/324 catches this on sub-page block size ext4. Fixes: bcff2488 ("ext4: don't read blocks from disk after extentsbeing swapped") Signed-off-by:
Eryu Guan <guaneryu@gmail.com> Signed-off-by:
Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Bjørn Mork authored
commit 4d06dd53 upstream. usbnet_link_change will call schedule_work and should be avoided if bind is failing. Otherwise we will end up with scheduled work referring to a netdev which has gone away. Instead of making the call conditional, we can just defer it to usbnet_probe, using the driver_info flag made for this purpose. Fixes: 8a34b0ae ("usbnet: cdc_ncm: apply usbnet_link_change") Reported-by:
Andrey Konovalov <andreyknvl@gmail.com> Suggested-by:
Bjørn Mork <bjorn@mork.no> Signed-off-by:
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Dan Carpenter authored
commit 1d3cd177 upstream. We accidentally return IS_ERR(priv->base) which is 1 instead of PTR_ERR(priv->base) which is the error code. Fixes: 6c821bd9 ('net: Add MOXA ART SoCs ethernet driver') Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Acked-by:
Arnd Bergmann <arnd@arndb.de> Signed-off-by:
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Florian Westphal authored
commit 5d150a98 upstream. When ipv6_find_hdr is used to find a fragment header (caller specifies target NEXTHDR_FRAGMENT) we erronously return -ENOENT for all fragments with nonzero offset. Before commit 9195bb8e, when target was specified, we did not enter the exthdr walk loop as nexthdr == target so this used to work. Now we do (so we can skip empty route headers). When we then stumble upon a frag with nonzero frag_off we must return -ENOENT ("header not found") only if the caller did not specifically request NEXTHDR_FRAGMENT. This allows nfables exthdr expression to match ipv6 fragments, e.g. via nft add rule ip6 filter input frag frag-off gt 0 Fixes: 9195bb8e ("ipv6: improve ipv6_find_hdr() to skip empty routing headers") Signed-off-by:
Florian Westphal <fw@strlen.de> Signed-off-by:
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Benjamin Poirier authored
commit 1837b2e2 upstream. The current reserved_tailroom calculation fails to take hlen and tlen into account. skb: [__hlen__|__data____________|__tlen___|__extra__] ^ ^ head skb_end_offset In this representation, hlen + data + tlen is the size passed to alloc_skb. "extra" is the extra space made available in __alloc_skb because of rounding up by kmalloc. We can reorder the representation like so: [__hlen__|__data____________|__extra__|__tlen___] ^ ^ head skb_end_offset The maximum space available for ip headers and payload without fragmentation is min(mtu, data + extra). Therefore, reserved_tailroom = data + extra + tlen - min(mtu, data + extra) = skb_end_offset - hlen - min(mtu, skb_end_offset - hlen - tlen) = skb_tailroom - min(mtu, skb_tailroom - tlen) ; after skb_reserve(hlen) Compare the second line to the current expression: reserved_tailroom = skb_end_offset - min(mtu, skb_end_offset) and we can see that hlen and tlen are not taken into account. The min() in the third line can be expanded into: if mtu < skb_tailroom - tlen: reserved_tailroom = skb_tailroom - mtu else: reserved_tailroom = tlen Depending on hlen, tlen, mtu and the number of multicast address records, the current code may output skbs that have less tailroom than dev->needed_tailroom or it may output more skbs than needed because not all space available is used. Fixes: 4c672e4b ("ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs") Signed-off-by:
Benjamin Poirier <bpoirier@suse.com> Acked-by:
Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by:
Daniel Borkmann <daniel@iogearbox.net> Signed-off-by:
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Jack Morgenstein authored
commit 6e522422 upstream. The VF administrative mac addresses (stored in the PF driver) are initialized to zero when the PF driver starts up. These addresses may be modified in the PF driver through ndo calls initiated by iproute2 or libvirt. While we allow the PF/host to change the VF admin mac address from zero to a valid unicast mac, we do not allow restoring the VF admin mac to zero. We currently only allow changing this mac to a different unicast mac. This leads to problems when libvirt scripts are used to deal with VF mac addresses, and libvirt attempts to revoke the mac so this host will not use it anymore. Fix this by allowing resetting a VF administrative MAC back to zero. Fixes: 8f7ba3ca ('net/mlx4: Add set VF mac address support') Signed-off-by:
Jack Morgenstein <jackm@dev.mellanox.co.il> Reported-by:
Moshe Levi <moshele@mellanox.com> Signed-off-by:
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Konstantin Khlebnikov authored
commit 9bdfb3b7 upstream. Currently it's converted into msecs, thus HZ=1000 intact. Signed-off-by:
Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: 740b0f18 ("tcp: switch rtt estimations to usec resolution") Signed-off-by:
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Alex Deucher authored
commit d74e766e upstream. This reverts commit 39d42750. This caused a regression on some older hardware. bug: https://bugzilla.kernel.org/show_bug.cgi?id=113891Signed-off-by:
Alex Deucher <alexander.deucher@amd.com> Signed-off-by:
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Radim Krčmář authored
commit 7099e2e1 upstream. Linux guests on Haswell (and also SandyBridge and Broadwell, at least) would crash if you decided to run a host command that uses PEBS, like perf record -e 'cpu/mem-stores/pp' -a This happens because KVM is using VMX MSR switching to disable PEBS, but SDM [2015-12] 18.4.4.4 Re-configuring PEBS Facilities explains why it isn't safe: When software needs to reconfigure PEBS facilities, it should allow a quiescent period between stopping the prior event counting and setting up a new PEBS event. The quiescent period is to allow any latent residual PEBS records to complete its capture at their previously specified buffer address (provided by IA32_DS_AREA). There might not be a quiescent period after the MSR switch, so a CPU ends up using host's MSR_IA32_DS_AREA to access an area in guest's memory. (Or MSR switching is just buggy on some models.) The guest can learn something about the host this way: If the guest doesn't map address pointed by MSR_IA32_DS_AREA, it results in #PF where we leak host's MSR_IA32_DS_AREA through CR2. After that, a malicious guest can map and configure memory where MSR_IA32_DS_AREA is pointing and can therefore get an output from host's tracing. This is not a critical leak as the host must initiate with PEBS tracing and I have not been able to get a record from more than one instruction before vmentry in vmx_vcpu_run() (that place has most registers already overwritten with guest's). We could disable PEBS just few instructions before vmentry, but disabling it earlier shouldn't affect host tracing too much. We also don't need to switch MSR_IA32_PEBS_ENABLE on VMENTRY, but that optimization isn't worth its code, IMO. (If you are implementing PEBS for guests, be sure to handle the case where both host and guest enable PEBS, because this patch doesn't.) Fixes: 26a4f3c0 ("perf/x86: disable PEBS on a guest entry.") Reported-by:
Jiří Olša <jolsa@redhat.com> Signed-off-by:
Radim Krčmář <rkrcmar@redhat.com> Signed-off-by:
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Paul Mackerras authored
commit ccec4456 upstream. Thomas Huth discovered that a guest could cause a hard hang of a host CPU by setting the Instruction Authority Mask Register (IAMR) to a suitable value. It turns out that this is because when the code was added to context-switch the new special-purpose registers (SPRs) that were added in POWER8, we forgot to add code to ensure that they were restored to a sane value on guest exit. This adds code to set those registers where a bad value could compromise the execution of the host kernel to a suitable neutral value on guest exit. Fixes: b005255eReported-by:
Thomas Huth <thuth@redhat.com> Reviewed-by:
David Gibson <david@gibson.dropbear.id.au> Signed-off-by:
Paul Mackerras <paulus@samba.org> Signed-off-by:
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