- 13 Feb, 2021 10 commits
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Dmitrii Banshchikov authored
Add an ability to pass a pointer to a type with known size in arguments of a global function. Such pointers may be used to overcome the limit on the maximum number of arguments, avoid expensive and tricky workarounds and to have multiple output arguments. A referenced type may contain pointers but indirect access through them isn't supported. The implementation consists of two parts. If a global function has an argument that is a pointer to a type with known size then: 1) In btf_check_func_arg_match(): check that the corresponding register points to NULL or to a valid memory region that is large enough to contain the expected argument's type. 2) In btf_prepare_func_args(): set the corresponding register type to PTR_TO_MEM_OR_NULL and its size to the size of the expected type. Only global functions are supported because allowance of pointers for static functions might break validation. Consider the following scenario. A static function has a pointer argument. A caller passes pointer to its stack memory. Because the callee can change referenced memory verifier cannot longer assume any particular slot type of the caller's stack memory hence the slot type is changed to SLOT_MISC. If there is an operation that relies on slot type other than SLOT_MISC then verifier won't be able to infer safety of the operation. When verifier sees a static function that has a pointer argument different from PTR_TO_CTX then it skips arguments check and continues with "inline" validation with more information available. The operation that relies on the particular slot type now succeeds. Because global functions were not allowed to have pointer arguments different from PTR_TO_CTX it's not possible to break existing and valid code. Signed-off-by:
Dmitrii Banshchikov <me@ubique.spb.ru> Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Acked-by:
Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210212205642.620788-4-me@ubique.spb.ru
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Dmitrii Banshchikov authored
Extract conversion from a register's nullable type to a type with a value. The helper will be used in mark_ptr_not_null_reg(). Signed-off-by:
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Dmitrii Banshchikov authored
Using "reg" for an array of bpf_reg_state and "reg[i + 1]" for an individual bpf_reg_state is error-prone and verbose. Use "regs" for the former and "reg" for the latter as other code nearby does. Signed-off-by:
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Jesper Dangaard Brouer authored
Adding selftest for BPF-helper bpf_check_mtu(). Making sure it can be used from both XDP and TC. V16: - Fix 'void' function definition V11: - Addresse nitpicks from Andrii Nakryiko V10: - Remove errno non-zero test in CHECK_ATTR() - Addresse comments from Andrii Nakryiko Signed-off-by:
Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
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Jesper Dangaard Brouer authored
This demonstrate how bpf_check_mtu() helper can easily be used together with bpf_skb_adjust_room() helper, prior to doing size adjustment, as delta argument is already setup. Hint: This specific test can be selected like this: ./test_progs -t cls_redirect Signed-off-by:
John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/161287791481.790810.4444271170546646080.stgit@firesoul
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Jesper Dangaard Brouer authored
The use-case for dropping the MTU check when TC-BPF does redirect to ingress, is described by Eyal Birger in email[0]. The summary is the ability to increase packet size (e.g. with IPv6 headers for NAT64) and ingress redirect packet and let normal netstack fragment packet as needed. [0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/ V15: - missing static for function declaration V9: - Make net_device "up" (IFF_UP) check explicit in skb_do_redirect V4: - Keep net_device "up" (IFF_UP) check. - Adjustment to handle bpf_redirect_peer() helper Signed-off-by:
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Jesper Dangaard Brouer authored
This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs. The SKB object is complex and the skb->len value (accessible from BPF-prog) also include the length of any extra GRO/GSO segments, but without taking into account that these GRO/GSO segments get added transport (L4) and network (L3) headers before being transmitted. Thus, this BPF-helper is created such that the BPF-programmer don't need to handle these details in the BPF-prog. The API is designed to help the BPF-programmer, that want to do packet context size changes, which involves other helpers. These other helpers usually does a delta size adjustment. This helper also support a delta size (len_diff), which allow BPF-programmer to reuse arguments needed by these other helpers, and perform the MTU check prior to doing any actual size adjustment of the packet context. It is on purpose, that we allow the len adjustment to become a negative result, that will pass the MTU check. This might seem weird, but it's not this helpers responsibility to "catch" wrong len_diff adjustments. Other helpers will take care of these checks, if BPF-programmer chooses to do actual size adjustment. V14: - Improve man-page desc of len_diff. V13: - Enforce flag BPF_MTU_CHK_SEGS cannot use len_diff. V12: - Simplify segment check that calls skb_gso_validate_network_len. - Helpers should return long V9: - Use dev->hard_header_len (instead of ETH_HLEN) - Annotate with unlikely req from Daniel - Fix logic error using skb_gso_validate_network_len from Daniel V6: - Took John's advice and dropped BPF_MTU_CHK_RELAX - Returned MTU is kept at L3-level (like fib_lookup) V4: Lot of changes - ifindex 0 now use current netdev for MTU lookup - rename helper from bpf_mtu_check to bpf_check_mtu - fix bug for GSO pkt length (as skb->len is total len) - remove __bpf_len_adj_positive, simply allow negative len adj Signed-off-by:
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Jesper Dangaard Brouer authored
The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup) can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog don't know the MTU value that caused this rejection. If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it need to know this MTU value for the ICMP packet. Patch change lookup and result struct bpf_fib_lookup, to contain this MTU value as output via a union with 'tot_len' as this is the value used for the MTU lookup. V5: - Fixed uninit value spotted by Dan Carpenter. - Name struct output member mtu_result Reported-by:
kernel test robot <lkp@intel.com> Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
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Jesper Dangaard Brouer authored
BPF end-user on Cilium slack-channel (Carlo Carraro) wants to use bpf_fib_lookup for doing MTU-check, but *prior* to extending packet size, by adjusting fib_params 'tot_len' with the packet length plus the expected encap size. (Just like the bpf_check_mtu helper supports). He discovered that for SKB ctx the param->tot_len was not used, instead skb->len was used (via MTU check in is_skb_forwardable() that checks against netdev MTU). Fix this by using fib_params 'tot_len' for MTU check. If not provided (e.g. zero) then keep existing TC behaviour intact. Notice that 'tot_len' for MTU check is done like XDP code-path, which checks against FIB-dst MTU. V16: - Revert V13 optimization, 2nd lookup is against egress/resulting netdev V13: - Only do ifindex lookup one time, calling dev_get_by_index_rcu(). V10: - Use same method as XDP for 'tot_len' MTU check Fixes: 4c79579b ("bpf: Change bpf_fib_lookup to return lookup status") Reported-by:
Carlo Carraro <colrack@gmail.com> Signed-off-by:
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Jesper Dangaard Brouer authored
Multiple BPF-helpers that can manipulate/increase the size of the SKB uses __bpf_skb_max_len() as the max-length. This function limit size against the current net_device MTU (skb->dev->mtu). When a BPF-prog grow the packet size, then it should not be limited to the MTU. The MTU is a transmit limitation, and software receiving this packet should be allowed to increase the size. Further more, current MTU check in __bpf_skb_max_len uses the MTU from ingress/current net_device, which in case of redirects uses the wrong net_device. This patch keeps a sanity max limit of SKB_MAX_ALLOC (16KiB). The real limit is elsewhere in the system. Jesper's testing[1] showed it was not possible to exceed 8KiB when expanding the SKB size via BPF-helper. The limiting factor is the define KMALLOC_MAX_CACHE_SIZE which is 8192 for SLUB-allocator (CONFIG_SLUB) in-case PAGE_SIZE is 4096. This define is in-effect due to this being called from softirq context see code __gfp_pfmemalloc_flags() and __do_kmalloc_node(). Jakub's testing showed that frames above 16KiB can cause NICs to reset (but not crash). Keep this sanity limit at this level as memory layer can differ based on kernel config. [1] https://github.com/xdp-project/bpf-examples/tree/master/MTU-testsSigned-off-by:
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- 12 Feb, 2021 18 commits
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Jun'ichi Nomura authored
The devmap bulk queue is allocated with GFP_ATOMIC and the allocation may fail if there is no available space in existing percpu pool. Since commit 75ccae62 ("xdp: Move devmap bulk queue into struct net_device") moved the bulk queue allocation to NETDEV_REGISTER callback, whose context is allowed to sleep, use GFP_KERNEL instead of GFP_ATOMIC to let percpu allocator extend the pool when needed and avoid possible failure of netdev registration. As the required alignment is natural, we can simply use alloc_percpu(). Fixes: 75ccae62 ("xdp: Move devmap bulk queue into struct net_device") Signed-off-by:
Jun'ichi Nomura <junichi.nomura@nec.com> Signed-off-by:
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Yonghong Song authored
Commit 15d83c4d ("bpf: Allow loading of a bpf_iter program") cached btf_id in struct bpf_iter_target_info so later on if it can be checked cheaply compared to checking registered names. syzbot found a bug that uninitialized value may occur to bpf_iter_target_info->btf_id. This is because we allocated bpf_iter_target_info structure with kmalloc and never initialized field btf_id afterwards. This uninitialized btf_id is typically compared to a u32 bpf program func proto btf_id, and the chance of being equal is extremely slim. This patch fixed the issue by using kzalloc which will also prevent future likely instances due to adding new fields. Fixes: 15d83c4d ("bpf: Allow loading of a bpf_iter program") Reported-by: syzbot+580f4f2a272e452d55cb@syzkaller.appspotmail.com Signed-off-by:
Yonghong Song <yhs@fb.com> Signed-off-by:
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Stanislav Fomichev authored
This is what I see after compiling the kernel: # bpf-next...bpf-next/master ?? tools/bpf/resolve_btfids/libbpf/ Fixes: fc6b48f6 ("tools/resolve_btfids: Build libbpf and libsubcmd in separate directories") Signed-off-by:
Stanislav Fomichev <sdf@google.com> Signed-off-by:
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Alexei Starovoitov authored
Song Liu says: ==================== This set introduces bpf_iter for task_vma, which can be used to generate information similar to /proc/pid/maps. Patch 4/4 adds an example that mimics /proc/pid/maps. Current /proc/<pid>/maps and /proc/<pid>/smaps provide information of vma's of a process. However, these information are not flexible enough to cover all use cases. For example, if a vma cover mixed 2MB pages and 4kB pages (x86_64), there is no easy way to tell which address ranges are backed by 2MB pages. task_vma solves the problem by enabling the user to generate customize information based on the vma (and vma->vm_mm, vma->vm_file, etc.). Changes v6 => v7: 1. Let BPF iter program use bpf_d_path without specifying sleepable. (Alexei) Changes v5 => v6: 1. Add more comments for task_vma_seq_get_next() to explain the logic of find_vma() calls. (Alexei) 2. Skip vma found by find_vma() when both vm_start and vm_end matches prev_vm_[start|end]. Previous versions only compares vm_start. IOW, if vma of [4k, 8k] is replaced by [4k, 12k] after relocking mmap_lock, v5 will skip the new vma, while v6 will process it. Changes v4 => v5: 1. Fix a refcount leak on task_struct. (Yonghong) 2. Fix the selftest. (Yonghong) Changes v3 => v4: 1. Avoid skipping vma by assigning invalid prev_vm_start in task_vma_seq_stop(). (Yonghong) 2. Move "again" label in task_vma_seq_get_next() save a check. (Yonghong) Changes v2 => v3: 1. Rewrite 1/4 so that we hold mmap_lock while calling BPF program. This enables the BPF program to access the real vma with BTF. (Alexei) 2. Fix the logic when the control is returned to user space. (Yonghong) 3. Revise commit log and cover letter. (Yonghong) Changes v1 => v2: 1. Small fixes in task_iter.c and the selftests. (Yonghong) ==================== Signed-off-by: -
Song Liu authored
The test dumps information similar to /proc/pid/maps. The first line of the output is compared against the /proc file to make sure they match. Signed-off-by:
Song Liu <songliubraving@fb.com> Signed-off-by:
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Song Liu authored
task_file and task_vma iter programs have access to file->f_path. Enable bpf_d_path to print paths of these file. Signed-off-by:
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Song Liu authored
Introduce task_vma bpf_iter to print memory information of a process. It can be used to print customized information similar to /proc/<pid>/maps. Current /proc/<pid>/maps and /proc/<pid>/smaps provide information of vma's of a process. However, these information are not flexible enough to cover all use cases. For example, if a vma cover mixed 2MB pages and 4kB pages (x86_64), there is no easy way to tell which address ranges are backed by 2MB pages. task_vma solves the problem by enabling the user to generate customize information based on the vma (and vma->vm_mm, vma->vm_file, etc.). To access the vma safely in the BPF program, task_vma iterator holds target mmap_lock while calling the BPF program. If the mmap_lock is contended, task_vma unlocks mmap_lock between iterations to unblock the writer(s). This lock contention avoidance mechanism is similar to the one used in show_smaps_rollup(). Signed-off-by:
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Martin KaFai Lau authored
This patch adds a "void *owner" member. The existing bpf_tcp_ca test will ensure the bpf_cubic.o and bpf_dctcp.o can be loaded. Signed-off-by:
Martin KaFai Lau <kafai@fb.com> Signed-off-by:
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Martin KaFai Lau authored
When libbpf initializes the kernel's struct_ops in "bpf_map__init_kern_struct_ops()", it enforces all pointer types must be a function pointer and rejects others. It turns out to be too strict. For example, when directly using "struct tcp_congestion_ops" from vmlinux.h, it has a "struct module *owner" member and it is set to NULL in a bpf_tcp_cc.o. Instead, it only needs to ensure the member is a function pointer if it has been set (relocated) to a bpf-prog. This patch moves the "btf_is_func_proto(kern_mtype)" check after the existing "if (!prog) { continue; }". The original debug message in "if (!prog) { continue; }" is also removed since it is no longer valid. Beside, there is a later debug message to tell which function pointer is set. The "btf_is_func_proto(mtype)" has already been guaranteed in "bpf_object__collect_st_ops_relos()" which has been run before "bpf_map__init_kern_struct_ops()". Thus, this check is removed. v2: - Remove outdated debug message (Andrii) Remove because there is a later debug message to tell which function pointer is set. - Following mtype->type is no longer needed. Remove: "skip_mods_and_typedefs(btf, mtype->type, &mtype_id)" - Do "if (!prog)" test before skip_mods_and_typedefs. Fixes: 590a0088 ("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: -
Stanislav Fomichev authored
We have the environments where usage of AF_INET is prohibited (cgroup/sock_create returns EPERM for AF_INET). Let's use AF_LOCAL instead of AF_INET, it should perfectly work with SIOCETHTOOL. Signed-off-by:
Björn Töpel <bjorn.topel@intel.com> Acked-by:
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Ilya Leoshkevich authored
All 32-bit variants of BPF_FETCH (add, and, or, xor, xchg, cmpxchg) define a 32-bit subreg and thus have zext_dst set. Their encoding, however, uses dst_reg field as a base register, which causes opt_subreg_zext_lo32_rnd_hi32() to zero-extend said base register instead of the one the insn really defines (r0 or src_reg). Fix by properly choosing a register being defined, similar to how check_atomic() already does that. Signed-off-by:
Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by:
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Ilya Leoshkevich authored
Based on [1], BPF_CMPXCHG should always load the old value into R0. The phrasing in bpf.rst is somewhat ambiguous in this regard, improve it to make this aspect crystal clear. [1] https://lore.kernel.org/bpf/CAADnVQJFcFwxEz=wnV=hkie-EDwa8s5JGbBQeFt1TGux1OihJw@mail.gmail.com/Signed-off-by:
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Alexei Starovoitov authored
bpf_prog_realloc copies contents of struct bpf_prog. The pointers have to be cleared before freeing old struct. Reported-by:
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Florent Revest authored
This builds up on the existing socket cookie test which checks whether the bpf_get_socket_cookie helpers provide the same value in cgroup/connect6 and sockops programs for a socket created by the userspace part of the test. Instead of having an update_cookie sockops program tag a socket local storage with 0xFF, this uses both an update_cookie_sockops program and an update_cookie_tracing program which succesively tag the socket with 0x0F and then 0xF0. Signed-off-by:
Florent Revest <revest@chromium.org> Signed-off-by:
KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210210111406.785541-5-revest@chromium.org
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Florent Revest authored
When migrating from the bpf.h's to the vmlinux.h's definition of struct bps_sock, an interesting LLVM behavior happened. LLVM started producing two fetches of ctx->sk in the sockops program this means that the verifier could not keep track of the NULL-check on ctx->sk. Therefore, we need to extract ctx->sk in a variable before checking and dereferencing it. Signed-off-by:
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Florent Revest authored
Currently, the selftest for the BPF socket_cookie helpers is built and run independently from test_progs. It's easy to forget and hard to maintain. This patch moves the socket cookies test into prog_tests/ and vastly simplifies its logic by: - rewriting the loading code with BPF skeletons - rewriting the server/client code with network helpers - rewriting the cgroup code with test__join_cgroup - rewriting the error handling code with CHECKs Signed-off-by:
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Florent Revest authored
This needs a new helper that: - can work in a sleepable context (using sock_gen_cookie) - takes a struct sock pointer and checks that it's not NULL Signed-off-by:
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Florent Revest authored
Since "92acdc58 bpf, net: Rework cookie generator as per-cpu one" socket cookies are not guaranteed to be non-decreasing. The bpf_get_socket_cookie helper descriptions are currently specifying that cookies are non-decreasing but we don't want users to rely on that. Reported-by:
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- 11 Feb, 2021 10 commits
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Jiri Olsa authored
Nathan reported issue with cleaning empty build directory: $ make -s O=build distclean ../../scripts/Makefile.include:4: *** \ O=/ho...build/tools/bpf/resolve_btfids does not exist. Stop. The problem that tools scripts require existing output directory, otherwise it fails. Adding check around the resolve_btfids clean target to ensure the output directory is in place. Signed-off-by:
Jiri Olsa <jolsa@kernel.org> Signed-off-by:
Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/bpf/20210211124004.1144344-1-jolsa@kernel.org
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Alexei Starovoitov authored
Add a basic test for map-in-map and per-cpu maps in sleepable programs. Signed-off-by:
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Alexei Starovoitov authored
Since sleepable programs are now executing under migrate_disable the per-cpu maps are safe to use. The map-in-map were ok to use in sleepable from the time sleepable progs were introduced. Note that non-preallocated maps are still not safe, since there is no rcu_read_lock yet in sleepable programs and dynamically allocated map elements are relying on rcu protection. The sleepable programs have rcu_read_lock_trace instead. That limitation will be addresses in the future. Signed-off-by:
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Alexei Starovoitov authored
Since recursion_misses counter is available in bpf_prog_info improve the selftest to make sure it's counting correctly. Signed-off-by:
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Alexei Starovoitov authored
Add per-program counter for number of times recursion prevention mechanism was triggered and expose it via show_fdinfo and bpf_prog_info. Teach bpftool to print it. Signed-off-by:
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Alexei Starovoitov authored
Add recursive non-sleepable fentry program as a test. All attach points where sleepable progs can execute are non recursive so far. The recursion protection mechanism for sleepable cannot be activated yet. Signed-off-by:
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Alexei Starovoitov authored
Since both sleepable and non-sleepable programs execute under migrate_disable add recursion prevention mechanism to both types of programs when they're executed via bpf trampoline. Signed-off-by:
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Alexei Starovoitov authored
Since sleepable programs don't migrate from the cpu the excution stats can be computed for them as well. Reuse the same infrastructure for both sleepable and non-sleepable programs. run_cnt -> the number of times the program was executed. run_time_ns -> the program execution time in nanoseconds including the off-cpu time when the program was sleeping. Signed-off-by: -
Alexei Starovoitov authored
In older non-RT kernels migrate_disable() was the same as preempt_disable(). Since commit 74d862b6 ("sched: Make migrate_disable/enable() independent of RT") migrate_disable() is real and doesn't prevent sleeping. Running sleepable programs with migration disabled allows to add support for program stats and per-cpu maps later. Signed-off-by:
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Alexei Starovoitov authored
Move bpf_prog_stats from prog->aux into prog to avoid one extra load in critical path of program execution. Signed-off-by:
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- 10 Feb, 2021 2 commits
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Marco Elver authored
For double-checked locking in bpf_common_lru_push_free(), node->type is read outside the critical section and then re-checked under the lock. However, concurrent writes to node->type result in data races. For example, the following concurrent access was observed by KCSAN: write to 0xffff88801521bc22 of 1 bytes by task 10038 on cpu 1: __bpf_lru_node_move_in kernel/bpf/bpf_lru_list.c:91 __local_list_flush kernel/bpf/bpf_lru_list.c:298 ... read to 0xffff88801521bc22 of 1 bytes by task 10043 on cpu 0: bpf_common_lru_push_free kernel/bpf/bpf_lru_list.c:507 bpf_lru_push_free kernel/bpf/bpf_lru_list.c:555 ... Fix the data races where node->type is read outside the critical section (for double-checked locking) by marking the access with READ_ONCE() as well as ensuring the variable is only accessed once. Fixes: 3a08c2fd ("bpf: LRU List") Reported-by: syzbot+3536db46dfa58c573458@syzkaller.appspotmail.com Reported-by: syzbot+516acdb03d3e27d91bcd@syzkaller.appspotmail.com Signed-off-by:
Marco Elver <elver@google.com> Signed-off-by:
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Jiapeng Chong authored
Fix the following coccicheck warnings: ./tools/testing/selftests/bpf/xdpxceiver.c:954:28-30: WARNING !A || A && B is equivalent to !A || B. ./tools/testing/selftests/bpf/xdpxceiver.c:932:28-30: WARNING !A || A && B is equivalent to !A || B. ./tools/testing/selftests/bpf/xdpxceiver.c:909:28-30: WARNING !A || A && B is equivalent to !A || B. Reported-by:
Abaci Robot <abaci@linux.alibaba.com> Signed-off-by:
Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Signed-off-by:
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