diff options
| author | Yafang <laoar.shao@gmail.com> | 2023-04-13 05:52:48 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-24 19:32:38 +0300 |
| commit | 60039bf72f81638baa28652a11a68e9b0b7b5b2d (patch) | |
| tree | 3f0000c30feb74d4e114d5a891459aee19d87b0f /kernel/bpf | |
| parent | f2065b8b0a215bc6aa061287a2e3d9eab2446422 (diff) | |
| download | linux-60039bf72f81638baa28652a11a68e9b0b7b5b2d.tar.xz | |
bpf: Add preempt_count_{sub,add} into btf id deny list
[ Upstream commit c11bd046485d7bf1ca200db0e7d0bdc4bafdd395 ]
The recursion check in __bpf_prog_enter* and __bpf_prog_exit*
leave preempt_count_{sub,add} unprotected. When attaching trampoline to
them we get panic as follows,
[ 867.843050] BUG: TASK stack guard page was hit at 0000000009d325cf (stack is 0000000046a46a15..00000000537e7b28)
[ 867.843064] stack guard page: 0000 [#1] PREEMPT SMP NOPTI
[ 867.843067] CPU: 8 PID: 11009 Comm: trace Kdump: loaded Not tainted 6.2.0+ #4
[ 867.843100] Call Trace:
[ 867.843101] <TASK>
[ 867.843104] asm_exc_int3+0x3a/0x40
[ 867.843108] RIP: 0010:preempt_count_sub+0x1/0xa0
[ 867.843135] __bpf_prog_enter_recur+0x17/0x90
[ 867.843148] bpf_trampoline_6442468108_0+0x2e/0x1000
[ 867.843154] ? preempt_count_sub+0x1/0xa0
[ 867.843157] preempt_count_sub+0x5/0xa0
[ 867.843159] ? migrate_enable+0xac/0xf0
[ 867.843164] __bpf_prog_exit_recur+0x2d/0x40
[ 867.843168] bpf_trampoline_6442468108_0+0x55/0x1000
...
[ 867.843788] preempt_count_sub+0x5/0xa0
[ 867.843793] ? migrate_enable+0xac/0xf0
[ 867.843829] __bpf_prog_exit_recur+0x2d/0x40
[ 867.843837] BUG: IRQ stack guard page was hit at 0000000099bd8228 (stack is 00000000b23e2bc4..000000006d95af35)
[ 867.843841] BUG: IRQ stack guard page was hit at 000000005ae07924 (stack is 00000000ffd69623..0000000014eb594c)
[ 867.843843] BUG: IRQ stack guard page was hit at 00000000028320f0 (stack is 00000000034b6438..0000000078d1bcec)
[ 867.843842] bpf_trampoline_6442468108_0+0x55/0x1000
...
That is because in __bpf_prog_exit_recur, the preempt_count_{sub,add} are
called after prog->active is decreased.
Fixing this by adding these two functions into btf ids deny list.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Yafang <laoar.shao@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20230413025248.79764-1-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 872616107613..322a2ae8f88b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15133,6 +15133,10 @@ BTF_ID(func, migrate_enable) #if !defined CONFIG_PREEMPT_RCU && !defined CONFIG_TINY_RCU BTF_ID(func, rcu_read_unlock_strict) #endif +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE) +BTF_ID(func, preempt_count_add) +BTF_ID(func, preempt_count_sub) +#endif BTF_SET_END(btf_id_deny) static int check_attach_btf_id(struct bpf_verifier_env *env) |