diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2026-10-11 16:48:35 +0000 |
|---|---|---|
| committer | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-10-12 10:43:38 +0200 |
| commit | 87bfa22937000db29a9a09ec826ab7227eaf9e8c (patch) | |
| tree | 945c2c6da03751b44bbad5c077292046a4e0dc28 /include/linux | |
| parent | ac1dff2daebb04816766106740042e7ad92859dd (diff) | |
bpf: Reject BTF ids with the same address in tracing_multi link
check_dup_ids() rejects equal BTF ids, but different ids can resolve to
the same address. Aliases:
ffffffff8161b6b0 t __do_sys_munlockall
ffffffff8161b6b0 T __ia32_sys_munlockall
ffffffff8161b6b0 T __x64_sys_munlockall
or several BTF_KIND_FUNC with the same name that vmlinux BTF has when
CONFIG_DEBUG_INFO_BTF_INLINE is set.
Each id gets its own trampoline and register_fentry_multi() adds them to
data->reg with the same ip. update_ftrace_direct_add() checks that new
entries are not in direct_functions, but doesn't compare them with each
other, so the attach succeeds. At detach update_ftrace_direct_del() sees
that 'direct' of one of the entries doesn't match and returns -EINVAL:
WARNING: kernel/bpf/trampoline.c:1845 at bpf_trampoline_multi_detach+0x24c/0x280
Call Trace:
bpf_link_free+0x51/0x110
bpf_link_release+0x18/0x20
__fput+0x103/0x2d0
__x64_sys_close+0x3d/0x80
The images are freed anyway, while ftrace still calls them:
Oops: int3: 0000 [#1] SMP NOPTI
RIP: 0010:0xffffffffc042b201
Call Trace:
? __audit_syscall_exit+0x9/0x100
? do_syscall_64+0x5ab/0x5e0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Kernel panic - not syncing: Fatal exception in interrupt
Return -EINVAL from register_fentry_multi() when ip is already in
data->reg. When such ids are attached via different links the second
attach already fails with -EINVAL in update_ftrace_direct_add().
Move the declaration of ftrace_lookup_ip() to include/linux/ftrace.h.
The lookup adds 60 msec to the attach of 64480 functions in
tracing_multi_bench_attach: 1.34 -> 1.40 sec.
Fixes: aef4dfa790b2 ("bpf: Add bpf_trampoline_multi_attach/detach functions")a
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20261011164836.2233874-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/ftrace.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index bd76a16a63af..b041d9142d2b 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -416,6 +416,7 @@ void free_ftrace_hash(struct ftrace_hash *hash); struct ftrace_func_entry *add_ftrace_hash_entry_direct(struct ftrace_hash *hash, unsigned long ip, unsigned long direct); void add_ftrace_hash_entry(struct ftrace_hash *hash, struct ftrace_func_entry *entry); +struct ftrace_func_entry *ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip); void ftrace_hash_remove(struct ftrace_hash *hash); /* The hash used to know what functions callbacks trace */ |