* [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic"
@ 2025-05-20 5:49 Xuewen Yan
2025-05-20 20:07 ` Alexei Starovoitov
2025-05-22 15:00 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 4+ messages in thread
From: Xuewen Yan @ 2025-05-20 5:49 UTC (permalink / raw)
To: song, jolsa, andrii, daniel, rostedt, ast, mhiramat
Cc: bpf, linux-kernel, linux-trace-kernel, xuewen.yan94, di.shen
From: Di Shen <di.shen@unisoc.com>
This reverts commit 4a8f635a60540888dab3804992e86410360339c8.
Althought get_pid_task() internally already calls rcu_read_lock() and
rcu_read_unlock(), the find_vpid() was not.
The documentation for find_vpid() clearly states:
"Must be called with the tasklist_lock or rcu_read_lock() held."
Add proper rcu_read_lock/unlock() to protect the find_vpid().
Reported-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Di Shen <di.shen@unisoc.com>
---
kernel/trace/bpf_trace.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 187dc37d61d4..0c4b6af10601 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3417,7 +3417,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
}
if (pid) {
+ rcu_read_lock();
task = get_pid_task(find_vpid(pid), PIDTYPE_TGID);
+ rcu_read_unlock();
if (!task) {
err = -ESRCH;
goto error_path_put;
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic"
2025-05-20 5:49 [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic" Xuewen Yan
@ 2025-05-20 20:07 ` Alexei Starovoitov
2025-05-20 20:30 ` Andrii Nakryiko
2025-05-22 15:00 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 4+ messages in thread
From: Alexei Starovoitov @ 2025-05-20 20:07 UTC (permalink / raw)
To: Xuewen Yan
Cc: Song Liu, Jiri Olsa, Andrii Nakryiko, Daniel Borkmann,
Steven Rostedt, Alexei Starovoitov, Masami Hiramatsu, bpf, LKML,
linux-trace-kernel, xuewen.yan94, di.shen
On Mon, May 19, 2025 at 10:51 PM Xuewen Yan <xuewen.yan@unisoc.com> wrote:
>
> From: Di Shen <di.shen@unisoc.com>
>
> This reverts commit 4a8f635a60540888dab3804992e86410360339c8.
>
> Althought get_pid_task() internally already calls rcu_read_lock() and
> rcu_read_unlock(), the find_vpid() was not.
>
> The documentation for find_vpid() clearly states:
>
> "Must be called with the tasklist_lock or rcu_read_lock() held."
>
> Add proper rcu_read_lock/unlock() to protect the find_vpid().
>
> Reported-by: Xuewen Yan <xuewen.yan@unisoc.com>
> Signed-off-by: Di Shen <di.shen@unisoc.com>
> ---
> kernel/trace/bpf_trace.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 187dc37d61d4..0c4b6af10601 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -3417,7 +3417,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> }
>
> if (pid) {
> + rcu_read_lock();
> task = get_pid_task(find_vpid(pid), PIDTYPE_TGID);
> + rcu_read_unlock();
> if (!task) {
> err = -ESRCH;
> goto error_path_put;
hmm. indeed.
Jiri ?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic"
2025-05-20 20:07 ` Alexei Starovoitov
@ 2025-05-20 20:30 ` Andrii Nakryiko
0 siblings, 0 replies; 4+ messages in thread
From: Andrii Nakryiko @ 2025-05-20 20:30 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Xuewen Yan, Song Liu, Jiri Olsa, Andrii Nakryiko, Daniel Borkmann,
Steven Rostedt, Alexei Starovoitov, Masami Hiramatsu, bpf, LKML,
linux-trace-kernel, xuewen.yan94, di.shen
On Tue, May 20, 2025 at 1:08 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Mon, May 19, 2025 at 10:51 PM Xuewen Yan <xuewen.yan@unisoc.com> wrote:
> >
> > From: Di Shen <di.shen@unisoc.com>
> >
> > This reverts commit 4a8f635a60540888dab3804992e86410360339c8.
> >
> > Althought get_pid_task() internally already calls rcu_read_lock() and
> > rcu_read_unlock(), the find_vpid() was not.
> >
> > The documentation for find_vpid() clearly states:
> >
> > "Must be called with the tasklist_lock or rcu_read_lock() held."
> >
> > Add proper rcu_read_lock/unlock() to protect the find_vpid().
> >
> > Reported-by: Xuewen Yan <xuewen.yan@unisoc.com>
> > Signed-off-by: Di Shen <di.shen@unisoc.com>
> > ---
> > kernel/trace/bpf_trace.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 187dc37d61d4..0c4b6af10601 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -3417,7 +3417,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> > }
> >
> > if (pid) {
> > + rcu_read_lock();
> > task = get_pid_task(find_vpid(pid), PIDTYPE_TGID);
> > + rcu_read_unlock();
> > if (!task) {
> > err = -ESRCH;
> > goto error_path_put;
>
> hmm. indeed.
>
yep, my bad, missed find_vpid() restrictions. revert LGTM
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> Jiri ?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic"
2025-05-20 5:49 [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic" Xuewen Yan
2025-05-20 20:07 ` Alexei Starovoitov
@ 2025-05-22 15:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-05-22 15:00 UTC (permalink / raw)
To: Xuewen Yan
Cc: song, jolsa, andrii, daniel, rostedt, ast, mhiramat, bpf,
linux-kernel, linux-trace-kernel, xuewen.yan94, di.shen
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:
On Tue, 20 May 2025 13:49:43 +0800 you wrote:
> From: Di Shen <di.shen@unisoc.com>
>
> This reverts commit 4a8f635a60540888dab3804992e86410360339c8.
>
> Althought get_pid_task() internally already calls rcu_read_lock() and
> rcu_read_unlock(), the find_vpid() was not.
>
> [...]
Here is the summary with links:
- Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic"
https://git.kernel.org/bpf/bpf-next/c/4e2e6841ff76
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-05-20 5:49 [PATCH] Revert "bpf: remove unnecessary rcu_read_{lock,unlock}() in multi-uprobe attach logic" Xuewen Yan
2025-05-20 20:07 ` Alexei Starovoitov
2025-05-20 20:30 ` Andrii Nakryiko
2025-05-22 15:00 ` patchwork-bot+netdevbpf
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