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bpf: Log error code on trampoline unlink failure

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Replace silent WARN_ON_ONCE with WARN_ONCE that prints the actual error
code from bpf_trampoline_unlink_prog(). This aids debugging of race
conditions during link teardown, while keeping the warning rate limited
to avoid log flooding.

This will be very helpful for speeding up trouble-shooting of some crash
UAF due to bpf_trampoline_unlink_prog failures.

No change to unlink behavior.

Signed-off-by: Xu Xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/bpf/20260729141159128mEJmS_aujBKr-cBu1p_UI@zte.com.cn
This commit is contained in:
Xu Xin
2026-07-29 14:11:59 +08:00
committed by Andrii Nakryiko
parent 863f3ddd0b
commit f0e80dee4e
2 changed files with 13 additions and 7 deletions
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8
kernel/bpf/syscall.c
View File

@@ -3555,10 +3555,12 @@ static void bpf_tracing_link_release(struct bpf_link *link)
{
struct bpf_tracing_link *tr_link =
container_of(link, struct bpf_tracing_link, link.link);
int err;
WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->link.node,
tr_link->trampoline,
tr_link->tgt_prog));
err = bpf_trampoline_unlink_prog(&tr_link->link.node,
tr_link->trampoline,
tr_link->tgt_prog);
WARN_ONCE(err, "bpf_trampoline_unlink_prog failed: %d\n", err);
bpf_trampoline_put(tr_link->trampoline);

12
kernel/bpf/trampoline.c
View File

@@ -1004,12 +1004,15 @@ static void bpf_shim_tramp_link_release(struct bpf_link *link)
{
struct bpf_shim_tramp_link *shim_link =
container_of(link, struct bpf_shim_tramp_link, link.link);
int err;
/* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */
if (!shim_link->trampoline)
return;
WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link.node, shim_link->trampoline, NULL));
err = bpf_trampoline_unlink_prog(&shim_link->link.node, shim_link->trampoline, NULL);
WARN_ONCE(err, "bpf_trampoline_unlink_prog failed: %d\n", err);
bpf_trampoline_put(shim_link->trampoline);
}
@@ -1720,15 +1723,16 @@ int bpf_trampoline_multi_detach(struct bpf_prog *prog, struct bpf_tracing_multi_
{
struct bpf_tracing_multi_data *data = &link->data;
struct bpf_tracing_multi_node *mnode;
int i;
int i, err;
trampoline_lock_all();
for_each_mnode(mnode, link) {
data->entry = &mnode->entry;
bpf_trampoline_multi_attach_init(mnode->trampoline);
WARN_ON_ONCE(__bpf_trampoline_unlink_prog(&mnode->node, mnode->trampoline,
NULL, &trampoline_multi_ops, data));
err = __bpf_trampoline_unlink_prog(&mnode->node, mnode->trampoline, NULL,
&trampoline_multi_ops, data);
WARN_ONCE(err, "__bpf_trampoline_unlink_prog failed: %d\n", err);
}
if (ftrace_hash_count(data->unreg))