diff options
| author | Jiri Olsa <olsajiri@gmail.com> | 2024-01-03 20:05:46 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-05 05:40:19 +0100 |
| commit | 715d82ba636cb3629a6e18a33bb9dbe53f9936ee (patch) | |
| tree | c164ed8ec5abb70af2adb3809e49542232ba26c6 /kernel/bpf | |
| parent | selftests/bpf: Add test for recursive attachment of tracing progs (diff) | |
| download | linux-715d82ba636cb3629a6e18a33bb9dbe53f9936ee.tar.xz linux-715d82ba636cb3629a6e18a33bb9dbe53f9936ee.zip | |
bpf: Fix re-attachment branch in bpf_tracing_prog_attach
The following case can cause a crash due to missing attach_btf:
1) load rawtp program
2) load fentry program with rawtp as target_fd
3) create tracing link for fentry program with target_fd = 0
4) repeat 3
In the end we have:
- prog->aux->dst_trampoline == NULL
- tgt_prog == NULL (because we did not provide target_fd to link_create)
- prog->aux->attach_btf == NULL (the program was loaded with attach_prog_fd=X)
- the program was loaded for tgt_prog but we have no way to find out which one
BUG: kernel NULL pointer dereference, address: 0000000000000058
Call Trace:
<TASK>
? __die+0x20/0x70
? page_fault_oops+0x15b/0x430
? fixup_exception+0x22/0x330
? exc_page_fault+0x6f/0x170
? asm_exc_page_fault+0x22/0x30
? bpf_tracing_prog_attach+0x279/0x560
? btf_obj_id+0x5/0x10
bpf_tracing_prog_attach+0x439/0x560
__sys_bpf+0x1cf4/0x2de0
__x64_sys_bpf+0x1c/0x30
do_syscall_64+0x41/0xf0
entry_SYSCALL_64_after_hwframe+0x6e/0x76
Return -EINVAL in this situation.
Fixes: f3a95075549e0 ("bpf: Allow trampoline re-attach for tracing and lsm programs")
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-4-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/syscall.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d15f9998bc20..a1f18681721c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3237,6 +3237,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * * - if prog->aux->dst_trampoline and tgt_prog is NULL, the program * was detached and is going for re-attachment. + * + * - if prog->aux->dst_trampoline is NULL and tgt_prog and prog->aux->attach_btf + * are NULL, then program was already attached and user did not provide + * tgt_prog_fd so we have no way to find out or create trampoline */ if (!prog->aux->dst_trampoline && !tgt_prog) { /* @@ -3250,6 +3254,11 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, err = -EINVAL; goto out_unlock; } + /* We can allow re-attach only if we have valid attach_btf. */ + if (!prog->aux->attach_btf) { + err = -EINVAL; + goto out_unlock; + } btf_id = prog->aux->attach_btf_id; key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, btf_id); } |