- 06 Jun, 2014 40 commits
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Kees Cook authored
This adds several behavioral tests to sysctl string and number writing to detect unexpected cases that behaved differently when the sysctl kernel.sysctl_writes_strict != 1. [ original ] root@localhost:~# make test_num == Testing sysctl behavior against /proc/sys/kernel/domainname == Writing test file ... ok Checking sysctl is not set to test value ... ok Writing sysctl from shell ... ok Resetting sysctl to original value ... ok Writing entire sysctl in single write ... ok Writing middle of sysctl after synchronized seek ... FAIL Writing beyond end of sysctl ... FAIL Writing sysctl with multiple long writes ... FAIL Writing entire sysctl in short writes ... FAIL Writing middle of sysctl after unsynchronized seek ... ok Checking sysctl maxlen is at least 65 ... ok Checking sysctl keeps original string on overflow append ... FAIL Checking sysctl stays NULL terminated on write ... ok Checking sysctl stays NULL terminated on overwrite ... ok make: *** [test_num] Error 1 root@localhost:~# make test_string == Testing sysctl behavior against /proc/sys/vm/swappiness == Writing test file ... ok Checking sysctl is not set to test value ... ok Writing sysctl from shell ... ok Resetting sysctl to original value ... ok Writing entire sysctl in single write ... ok Writing middle of sysctl after synchronized seek ... FAIL Writing beyond end of sysctl ... FAIL Writing sysctl with multiple long writes ... ok make: *** [test_string] Error 1 [ with CONFIG_PROC_SYSCTL_STRICT_WRITES ] root@localhost:~# make run_tests == Testing sysctl behavior against /proc/sys/kernel/domainname == Writing test file ... ok Checking sysctl is not set to test value ... ok Writing sysctl from shell ... ok Resetting sysctl to original value ... ok Writing entire sysctl in single write ... ok Writing middle of sysctl after synchronized seek ... ok Writing beyond end of sysctl ... ok Writing sysctl with multiple long writes ... ok Writing entire sysctl in short writes ... ok Writing middle of sysctl after unsynchronized seek ... ok Checking sysctl maxlen is at least 65 ... ok Checking sysctl keeps original string on overflow append ... ok Checking sysctl stays NULL terminated on write ... ok Checking sysctl stays NULL terminated on overwrite ... ok == Testing sysctl behavior against /proc/sys/vm/swappiness == Writing test file ... ok Checking sysctl is not set to test value ... ok Writing sysctl from shell ... ok Resetting sysctl to original value ... ok Writing entire sysctl in single write ... ok Writing middle of sysctl after synchronized seek ... ok Writing beyond end of sysctl ... ok Writing sysctl with multiple long writes ... ok Signed-off-by:Kees Cook <keescook@chromium.org> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Kees Cook authored
When writing to a sysctl string, each write, regardless of VFS position, begins writing the string from the start. This means the contents of the last write to the sysctl controls the string contents instead of the first: open("/proc/sys/kernel/modprobe", O_WRONLY) = 1 write(1, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"..., 4096) = 4096 write(1, "/bin/true", 9) = 9 close(1) = 0 $ cat /proc/sys/kernel/modprobe /bin/true Expected behaviour would be to have the sysctl be "AAAA..." capped at maxlen (in this case KMOD_PATH_LEN: 256), instead of truncating to the contents of the second write. Similarly, multiple short writes would not append to the sysctl. The old behavior is unlike regular POSIX files enough that doing audits of software that interact with sysctls can end up in unexpected or dangerous situations. For example, "as long as the input starts with a trusted path" turns out to be an insufficient filter, as what must also happen is for the input to be entirely contained in a single write syscall -- not a common consideration, especially for high level tools. This provides kernel.sysctl_writes_strict as a way to make this behavior act in a less surprising manner for strings, and disallows non-zero file position when writing numeric sysctls (similar to what is already done when reading from non-zero file positions). For now, the default (0) is to warn about non-zero file position use, but retain the legacy behavior. Setting this to -1 disables the warning, and setting this to 1 enables the file position respecting behavior. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: move misplaced hunk, per Randy] Signed-off-by: -
Kees Cook authored
Consolidate buffer length checking with new-line/end-of-line checking. Additionally, instead of reading user memory twice, just do the assignment during the loop. This change doesn't affect the potential races here. It was already possible to read a sysctl that was in the middle of a write. In both cases, the string will always be NULL terminated. The pre-existing race remains a problem to be solved. Signed-off-by:
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Kees Cook authored
When writing to a sysctl string, each write, regardless of VFS position, began writing the string from the start. This meant the contents of the last write to the sysctl controlled the string contents instead of the first. This misbehavior was featured in an exploit against Chrome OS. While it's not in itself a vulnerability, it's a weirdness that isn't on the mind of most auditors: "This filter looks correct, the first line written would not be meaningful to sysctl" doesn't apply here, since the size of the write and the contents of the final write are what matter when writing to sysctls. This adds the sysctl kernel.sysctl_writes_strict to control the write behavior. The default (0) reports when VFS position is non-0 on a write, but retains legacy behavior, -1 disables the warning, and 1 enables the position-respecting behavior. The long-term plan here is to wait for userspace to be fixed in response to the new warning and to then switch the default kernel behavior to the new position-respecting behavior. This patch (of 4): The char buffer arguments are needlessly cast in weird places. Clean it up so things are easier to read. Signed-off-by:
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Alexander Gordeev authored
As result of deprecation of MSI-X/MSI enablement functions pci_enable_msix() and pci_enable_msi_block() all drivers using these two interfaces need to be updated to use the new pci_enable_msi_range() or pci_enable_msi_exact() and pci_enable_msix_range() or pci_enable_msix_exact() interfaces. The patch has no runtime effect. Signed-off-by:
Alexander Gordeev <agordeev@redhat.com> Cc: Matt Porter <mporter@kernel.crashing.org> Acked-by:
Alexandre Bounine <alexandre.bounine@idt.com> Signed-off-by:
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Lai Jiangshan authored
idr_layer->layer is always accessed in read path, move it in the front. idr_layer->bitmap is moved on the bottom. And rcu_head shares with bitmap due to they do not be accessed at the same time. idr->id_free/id_free_cnt/lock are free list fields, and moved to the bottom. They will be removed in near future. Signed-off-by:
Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Lai Jiangshan authored
If "idr->hint == p" is true, it also implies "idr->hint" is true(not NULL). Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
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Lai Jiangshan authored
After idr subsystem is changed to RCU-awared, the free layer will not go to the free list. The free list will not be filled up when idr_remove(). So we don't need to shink it too. Signed-off-by:
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Lai Jiangshan authored
When the smaller id is not found, idr_replace() returns -ENOENT. But when the id is bigger enough, idr_replace() returns -EINVAL, actually there is no difference between these two kinds of ids. These are all unallocated id, the return values of the idr_replace() for these ids should be the same: -ENOENT. Signed-off-by:
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Lai Jiangshan authored
If the ida has at least one existing id, and when an unallocated ID which meets a certain condition is passed to the ida_remove(), the system will crash because it hits NULL pointer dereference. The condition is that the unallocated ID shares the same lowest idr layer with the existing ID, but the idr slot would be different if the unallocated ID were to be allocated. In this case the matching idr slot for the unallocated_id is NULL, causing @bitmap to be NULL which the function dereferences without checking crashing the kernel. See the test code: static void test3(void) { int id; DEFINE_IDA(test_ida); printk(KERN_INFO "Start test3\n"); if (ida_pre_get(&test_ida, GFP_KERNEL) < 0) return; if (ida_get_new(&test_ida, &id) < 0) return; ida_remove(&test_ida, 4000); /* bug: null deference here */ printk(KERN_INFO "End of test3\n"); } It happens only when the caller tries to free an unallocated ID which is the caller's fault. It is not a bug. But it is better to add the proper check and complain rather than crashing the kernel. [tj@kernel.org: updated patch description] Signed-off-by: -
Lai Jiangshan authored
If unallocated_id = (ANY * idr_max(idp->layers) + existing_id) is passed to idr_remove(). The existing_id will be removed unexpectedly. The following test shows this unexpected id-removal: static void test4(void) { int id; DEFINE_IDR(test_idr); printk(KERN_INFO "Start test4\n"); id = idr_alloc(&test_idr, (void *)1, 42, 43, GFP_KERNEL); BUG_ON(id != 42); idr_remove(&test_idr, 42 + IDR_SIZE); TEST_BUG_ON(idr_find(&test_idr, 42) != (void *)1); idr_destroy(&test_idr); printk(KERN_INFO "End of test4\n"); } ida_remove() shares the similar problem. It happens only when the caller tries to free an unallocated ID which is the caller's fault. It is not a bug. But it is better to add the proper check and complain rather than removing an existing_id silently. Signed-off-by: -
Lai Jiangshan authored
idr_replace() open-codes the logic to calculate the maximum valid ID given the height of the idr tree; unfortunately, the open-coded logic doesn't account for the fact that the top layer may have unused slots and over-shifts the limit to zero when the tree is at its maximum height. The following test code shows it fails to replace the value for id=((1<<27)+42): static void test5(void) { int id; DEFINE_IDR(test_idr); #define TEST5_START ((1<<27)+42) /* use the highest layer */ printk(KERN_INFO "Start test5\n"); id = idr_alloc(&test_idr, (void *)1, TEST5_START, 0, GFP_KERNEL); BUG_ON(id != TEST5_START); TEST_BUG_ON(idr_replace(&test_idr, (void *)2, TEST5_START) != (void *)1); idr_destroy(&test_idr); printk(KERN_INFO "End of test5\n"); } Fix the bug by using idr_max() which correctly takes into account the maximum allowed shift. sub_alloc() shares the same problem and may incorrectly fail with -EAGAIN; however, this bug doesn't affect correct operation because idr_get_empty_slot(), which already uses idr_max(), retries with the increased @id in such cases. [tj@kernel.org: Updated patch description.] Signed-off-by: -
Fabian Frederick authored
+ some pr_warning -> pr_warn and checkpatch warning fixes Signed-off-by:
Fabian Frederick <fabf@skynet.be> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by:
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Masami Hiramatsu authored
Add a "crash_kexec_post_notifiers" boot option to run kdump after running panic_notifiers and dump kmsg. This can help rare situations where kdump fails because of unstable crashed kernel or hardware failure (memory corruption on critical data/code), or the 2nd kernel is already broken by the 1st kernel (it's a broken behavior, but who can guarantee that the "crashed" kernel works correctly?). Usage: add "crash_kexec_post_notifiers" to kernel boot option. Note that this actually increases risks of the failure of kdump. This option should be set only if you worry about the rare case of kdump failure rather than increasing the chance of success. Signed-off-by:
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by:
Motohiro Kosaki <Motohiro.Kosaki@us.fujitsu.com> Acked-by:
Vivek Goyal <vgoyal@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Cc: Satoru MORIYA <satoru.moriya.br@hitachi.com> Cc: Tomoki Sekiyama <tomoki.sekiyama@hds.com> Signed-off-by:
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Srivatsa S. Bhat authored
There is a longstanding problem related to CPU hotplug which causes IPIs to be delivered to offline CPUs, and the smp-call-function IPI handler code prints out a warning whenever this is detected. Every once in a while this (usually harmless) warning gets reported on LKML, but so far it has not been completely fixed. Usually the solution involves finding out the IPI sender and fixing it by adding appropriate synchronization with CPU hotplug. However, while going through one such internal bug reports, I found that there is a significant bug in the receiver side itself (more specifically, in stop-machine) that can lead to this problem even when the sender code is perfectly fine. This patchset fixes that synchronization problem in the CPU hotplug stop-machine code. Patch 1 adds some additional debug code to the smp-call-function framework, to help debug such issues easily. Patch 2 modifies the stop-machine code to ensure that any IPIs that were sent while the target CPU was online, would be noticed and handled by that CPU without fail before it goes offline. Thus, this avoids scenarios where IPIs are received on offline CPUs (as long as the sender uses proper hotplug synchronization). In fact, I debugged the problem by using Patch 1, and found that the payload of the IPI was always the block layer's trigger_softirq() function. But I was not able to find anything wrong with the block layer code. That's when I started looking at the stop-machine code and realized that there is a race-window which makes the IPI _receiver_ the culprit, not the sender. Patch 2 fixes that race and hence this should put an end to most of the hard-to-debug IPI-to-offline-CPU issues. This patch (of 2): Today the smp-call-function code just prints a warning if we get an IPI on an offline CPU. This info is sufficient to let us know that something went wrong, but often it is very hard to debug exactly who sent the IPI and why, from this info alone. In most cases, we get the warning about the IPI to an offline CPU, immediately after the CPU going offline comes out of the stop-machine phase and reenables interrupts. Since all online CPUs participate in stop-machine, the information regarding the sender of the IPI is already lost by the time we exit the stop-machine loop. So even if we dump the stack on each CPU at this point, we won't find anything useful since all of them will show the stack-trace of the stopper thread. So we need a better way to figure out who sent the IPI and why. To achieve this, when we detect an IPI targeted to an offline CPU, loop through the call-single-data linked list and print out the payload (i.e., the name of the function which was supposed to be executed by the target CPU). This would give us an insight as to who might have sent the IPI and help us debug this further. [akpm@linux-foundation.org: correctly suppress warning output on second and later occurrences] Signed-off-by:
Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Galbraith <mgalbraith@suse.de> Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Signed-off-by:
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Fabian Frederick authored
Static values are automatically initialized to NULL. Signed-off-by:
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Fabian Frederick authored
Signed-off-by:
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Oleg Nesterov authored
Now that we have kernel_sigaction() we can change wait_for_helper() to use it and cleans up the code a bit. Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Richard Weinberger <richard@nod.at> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Oleg Nesterov authored
Now that allow_signal() is really trivial we can unify it with disallow_signal(). Add the new helper, kernel_sigaction(), and reimplement allow_signal/disallow_signal as a trivial wrappers. This saves one EXPORT_SYMBOL() and the new helper can have more users. Signed-off-by:
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Oleg Nesterov authored
disallow_signal() simply sets SIG_IGN, this is not enough and recalc_sigpending() is simply pointless because in can never change the state of TIF_SIGPENDING. If we ignore a signal, we also need to do flush_sigqueue_mask() for the case when this signal is pending, this way recalc_sigpending() can actually clear TIF_SIGPENDING and we do not "leak" the allocated siginfo's. Signed-off-by:
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Oleg Nesterov authored
allow_signal() does sigdelset(current->blocked) due to historic reason, previously it could be called by a daemonize()'ed kthread, and daemonize() played with current->blocked. Now that daemonize() has gone away we can remove sigdelset() and recalc_sigpending(). If a user really wants to unblock a signal, it must use sigprocmask() or set_current_block() explicitely. Signed-off-by:
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Oleg Nesterov authored
jffs2_garbage_collect_thread() does disallow_signal(SIGHUP) around jffs2_garbage_collect_pass() and the comment says "We don't want SIGHUP to interrupt us". But disallow_signal() can't ensure that jffs2_garbage_collect_pass() won't be interrupted by SIGHUP, the problem is that SIGHUP can be already pending when disallow_signal() is called, and in this case any interruptible sleep won't block. Note: this is in fact because disallow_signal() is buggy and should be fixed, see the next changes. But there is another reason why disallow_signal() is wrong: SIG_IGN set by disallow_signal() silently discards any SIGHUP which can be sent before the next allow_signal(SIGHUP). Change this code to use sigprocmask(SIG_UNBLOCK/SIG_BLOCK, SIGHUP). This even matches the old (and wrong) semantics allow/disallow had when this logic was written. Signed-off-by:
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Oleg Nesterov authored
Move the declaration/definition of allow_signal/disallow_signal to signal.h/signal.c. The new place is more logical and allows to use the static helpers in signal.c (see the next changes). While at it, make them return void and remove the valid_signal() check. Nobody checks the returned value, and in-kernel users must not pass the wrong signal number. Signed-off-by:
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Oleg Nesterov authored
The usage of "task_struct *t" and "current" in do_sigaction() looks really annoying and chaotic. Initially "t" is used as a cached value of current but not consistently, then it is reused as a loop variable and we have to use "current" again. Clean up this mess and also convert the code to use for_each_thread(). Signed-off-by:
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Oleg Nesterov authored
"rm_from_queue_full" looks ugly and misleading, especially now that rm_from_queue() has gone away. Rename it to flush_sigqueue_mask(), this matches flush_sigqueue() we already have. Also remove the obsolete comment which explains the difference with rm_from_queue() we already killed. Signed-off-by:
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Oleg Nesterov authored
rm_from_queue() doesn't make sense. The only caller, prepare_signal(), can use rm_from_queue_full() with the same effect. While at it, change prepare_signal() to use for_each_thread() instead of do/while_each_thread. Signed-off-by:
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Oleg Nesterov authored
Cosmetic, but siginitset(0) looks a bit strange, sigemptyset() is what do_sigtimedwait() needs. Signed-off-by:
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Oleg Nesterov authored
It has no users and it doesn't look useful. I do not know why/when it was introduced, I can't even find any user in the git history. Signed-off-by:
Geert Uytterhoeven <geert@linux-m68k.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Richard Weinberger <richard@nod.at> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Oleg Nesterov authored
__wake_up_bit() checks waitqueue_active() and thus the caller needs mb() as wake_up_bit() documents, fix task_clear_jobctl_trapping(). Signed-off-by:
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Matthew Dempsky authored
When tracing a process in another pid namespace, it's important for fork event messages to contain the child's pid as seen from the tracer's pid namespace, not the parent's. Otherwise, the tracer won't be able to correlate the fork event with later SIGTRAP signals it receives from the child. We still risk a race condition if a ptracer from a different pid namespace attaches after we compute the pid_t value. However, sending a bogus fork event message in this unlikely scenario is still a vast improvement over the status quo where we always send bogus fork event messages to debuggers in a different pid namespace than the forking process. Signed-off-by:
Matthew Dempsky <mdempsky@chromium.org> Acked-by:
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Alexey Dobriyan authored
Examples introducing neccesity of RMB+WMP pair reads as A=3 READ B www rrrrrr B=4 READ A Note the opposite order of reads vs writes. But the first example without barriers reads as A=3 READ A B=4 READ B There are 4 outcomes in the first example. But if someone new to the concept tries to insert barriers like this: A=3 READ A www rrrrrr B=4 READ B he will still get all 4 possible outcomes, because "READ A" is first. All this can be utterly confusing because barrier pair seems to be superfluous. In short, fixup first example to match latter examples with barriers. Signed-off-by:Alexey Dobriyan <adobriyan@gmail.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by:
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Fabian Frederick authored
Linked article in seq_file.txt still uses create_proc_entry which was removed in commit 80e928f7 ("proc: Kill create_proc_entry()"). This patch adds information for kernel 3.10 and above Signed-off-by:
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Jacob Keller authored
Update the SubmittingPatches process to include howto about the new 'Fixes:' tag to be used when a patch fixes an issue in a previous commit (found by git-bisect for example). Signed-off-by:
Jacob Keller <jacob.e.keller@intel.com> Tested-by:
Aaron Brown <aaron.f.brown@intel.com> Signed-off-by:
Jeff Kirsher <jeffrey.t.kirsher@intel.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by:
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Manuel Schölling authored
Initializations like 'char *foo = "bar"' will create two variables: a static string and a pointer (foo) to that static string. Instead 'char foo[] = "bar"' will declare a single variable and will end up in shorter assembly (according to Jeff Garzik on the KernelJanitor's TODO list). Signed-off-by:
Manuel Schölling <manuel.schoelling@gmx.de> Acked-by:
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by:
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Conrad Meyer authored
Add structure for parsed BPB information, struct fat_bios_param_block, and move all of the deserialization and validation logic from fat_fill_super() into fat_read_bpb(). Add a 'dos1xfloppy' mount option to infer DOS 2.x BIOS Parameter Block defaults from block device geometry for ancient floppies and floppy images, as a fall-back from the default BPB parsing logic. When fat_read_bpb() finds an invalid FAT filesystem and dos1xfloppy is set, fall back to fat_read_static_bpb(). fat_read_static_bpb() validates that the entire BPB is zero, and that the floppy has a DOS-style 8086 code bootstrapping header. Then it fills in default BPB values from media size and a table.[0] Media size is assumed to be static for archaic FAT volumes. See also: [1]. Fixes kernel.org bug #42617. [0]: https://en.wikipedia.org/wiki/File_Allocation_Table#Exceptions [1]: http://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html [hirofumi@mail.parknet.co.jp: fix missed error code] Signed-off-by:
Conrad Meyer <cse.cem@gmail.com> Acked-by:
Alan Cox <alan@linux.intel.com> Signed-off-by:
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Fabian Frederick authored
This patch applies a suggestion by Mikulas Patocka asking to increase all pr_warn without commented ones to pr_err Signed-off-by:
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Fabian Frederick authored
Normalize function display fx() using __func__ Signed-off-by:
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Fabian Frederick authored
Also remove redundant level names (warning:...) Signed-off-by:
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Fabian Frederick authored
No level printk in hptfs_error converted to pr_err (others to pr_warn or pr_info) This patch also fixes if/then/else checkpatch warnings Signed-off-by:
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Fabian Frederick authored
err is used in ufs_new_fragments (ufs_add_fragments only callsite) not in ufs_add_fragments. Signed-off-by:
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