2024-01-17 16:17:02

by David Howells

Subject: [PATCH] afs: Fix missing/incorrect unlocking of RCU read lock

In afs_proc_addr_prefs_show(), we need to unlock the RCU read lock in both
places before returning (and not lock it again).

Fixes: f94f70d39cc2 ("afs: Provide a way to configure address priorities")
Reported-by: Marc Dionne <[email protected]>
Signed-off-by: David Howells <[email protected]>
cc: [email protected]
cc: [email protected]
---
fs/afs/proc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 3bd02571f30d..15eab053af6d 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -166,7 +166,7 @@ static int afs_proc_addr_prefs_show(struct seq_file *m, void *v)

if (!preflist) {
seq_puts(m, "NO PREFS\n");
- return 0;
+ goto out;
}

seq_printf(m, "PROT SUBNET PRIOR (v=%u n=%u/%u/%u)\n",
@@ -191,7 +191,8 @@ static int afs_proc_addr_prefs_show(struct seq_file *m, void *v)
}
}

- rcu_read_lock();
+out:
+ rcu_read_unlock();
return 0;
}

2024-01-17 16:22:48

by David Howells

Subject: Re: [PATCH] afs: Fix missing/incorrect unlocking of RCU read lock

David Howells <[email protected]> wrote:

> In afs_proc_addr_prefs_show(), we need to unlock the RCU read lock in both
> places before returning (and not lock it again).
>
> Fixes: f94f70d39cc2 ("afs: Provide a way to configure address priorities")
> Reported-by: Marc Dionne <[email protected]>

Actually:

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
> Signed-off-by: David Howells <[email protected]>
> cc: [email protected]
> cc: [email protected]

David

2024-01-17 17:17:34

by Alan Huang

Subject: Re: [PATCH] afs: Fix missing/incorrect unlocking of RCU read lock

> 2024年1月18日 00:14，David Howells <[email protected]> 写道：
>
> In afs_proc_addr_prefs_show(), we need to unlock the RCU read lock in both
> places before returning (and not lock it again).
>
> Fixes: f94f70d39cc2 ("afs: Provide a way to configure address priorities")
> Reported-by: Marc Dionne <[email protected]>
> Signed-off-by: David Howells <[email protected]>
> cc: [email protected]
> cc: [email protected]
> ---
> fs/afs/proc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/afs/proc.c b/fs/afs/proc.c
> index 3bd02571f30d..15eab053af6d 100644
> --- a/fs/afs/proc.c
> +++ b/fs/afs/proc.c
> @@ -166,7 +166,7 @@ static int afs_proc_addr_prefs_show(struct seq_file *m, void *v)
>
> if (!preflist) {
> seq_puts(m, "NO PREFS\n");
> - return 0;
> + goto out;
> }
>
> seq_printf(m, "PROT SUBNET PRIOR (v=%u n=%u/%u/%u)\n",
> @@ -191,7 +191,8 @@ static int afs_proc_addr_prefs_show(struct seq_file *m, void *v)
> }
> }
>
> - rcu_read_lock();
> +out:
> + rcu_read_unlock();

What about using:

guard(rcu)();

Thanks,
Alan

> return 0;
> }
>
>