| Message ID | 20210728172307.1030271-1-yhs@fb.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 8118b11cb603afe853bc2e221c0d126899e715a9 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf] bpf: fix rcu warning in bpf_prog_run_pin_on_cpu() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | fail | 1 blamed authors not CCed: john.fastabend@gmail.com; 7 maintainers not CCed: netdev@vger.kernel.org kpsingh@kernel.org kafai@fb.com john.fastabend@gmail.com songliubraving@fb.com davem@davemloft.net kuba@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 13 this patch: 13 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 10 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 13 this patch: 13 |
| netdev/header_inline | success | Link |
Hello: This patch was applied to bpf/bpf.git (refs/heads/master): On Wed, 28 Jul 2021 10:23:07 -0700 you wrote: > syzbot reported a RCU warning like below: > WARNING: suspicious RCU usage > ... > Call Trace: > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 > task_css_set include/linux/cgroup.h:481 [inline] > task_dfl_cgroup include/linux/cgroup.h:550 [inline] > ____bpf_get_current_cgroup_id kernel/bpf/helpers.c:356 [inline] > bpf_get_current_cgroup_id+0x1ce/0x210 kernel/bpf/helpers.c:354 > bpf_prog_08c4887f705f20b8+0x10/0x824 > bpf_dispatcher_nop_func include/linux/bpf.h:687 [inline] > bpf_prog_run_pin_on_cpu include/linux/filter.h:624 [inline] > bpf_prog_test_run_syscall+0x2cf/0x5f0 net/bpf/test_run.c:954 > bpf_prog_test_run kernel/bpf/syscall.c:3207 [inline] > __sys_bpf+0x1993/0x53b0 kernel/bpf/syscall.c:4487 > > [...] Here is the summary with links: - [bpf] bpf: fix rcu warning in bpf_prog_run_pin_on_cpu() https://git.kernel.org/bpf/bpf/c/8118b11cb603 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 1cc75c811e24..a350b185d9d2 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -951,7 +951,10 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog, goto out; } } + + rcu_read_lock(); retval = bpf_prog_run_pin_on_cpu(prog, ctx); + rcu_read_unlock(); if (copy_to_user(&uattr->test.retval, &retval, sizeof(u32))) { err = -EFAULT;
syzbot reported a RCU warning like below: WARNING: suspicious RCU usage ... Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 task_css_set include/linux/cgroup.h:481 [inline] task_dfl_cgroup include/linux/cgroup.h:550 [inline] ____bpf_get_current_cgroup_id kernel/bpf/helpers.c:356 [inline] bpf_get_current_cgroup_id+0x1ce/0x210 kernel/bpf/helpers.c:354 bpf_prog_08c4887f705f20b8+0x10/0x824 bpf_dispatcher_nop_func include/linux/bpf.h:687 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:624 [inline] bpf_prog_test_run_syscall+0x2cf/0x5f0 net/bpf/test_run.c:954 bpf_prog_test_run kernel/bpf/syscall.c:3207 [inline] __sys_bpf+0x1993/0x53b0 kernel/bpf/syscall.c:4487 The warning is introduced by Commit 79a7f8bdb159d ("bpf: Introduce bpf_sys_bpf() helper and program type."). The rcu_read_lock/unlock() is missing when calling bpf_prog_run_pin_on_cpu(). Previously, bpf_prog_run_pin_on_cpu() is simply BPF_PROG_RUN macro and if necessary functions using BPF_PROG_RUN all have proper rcu_read_lock/unlock() protections. Commit 3c58482a382ba ("bpf: Provide bpf_prog_run_pin_on_cpu() helper") added bpf_prog_run_pin_on_cpu() helper in order to add migrate_disable/enable() support. Commit 79a7f8bdb159d later called bpf_prog_run_pin_on_cpu() but didn't have rcu_read_lock/unlock() at the callsite which triggered the reason. I added rcu lock protection in bpf_prog_test_run_syscall() which fixed the issue. Alternatively, rcu lock protection could be added in bpf_prog_test_run_syscall() and some rcu lock protection in bpf_prog_test_run_syscall() callers can be removed. I feel the later is a bigger change for bpf tree. So I picked the simpler solution. Reported-by: syzbot+7ee5c2c09c284495371f@syzkaller.appspotmail.com Fixes: 79a7f8bdb159d ("bpf: Introduce bpf_sys_bpf() helper and program type.") Signed-off-by: Yonghong Song <yhs@fb.com> --- net/bpf/test_run.c | 3 +++ 1 file changed, 3 insertions(+)