On Thu, Oct 31, 2024 at 04:56:01AM +0000, Andrei Vagin wrote:
> The inc_rlimit_get_ucounts() increments the specified rlimit counter and
> then checks its limit. If the value exceeds the limit, the function
> returns an error without decrementing the counter.
>
> Fixes: 15bc01effefe ("ucounts: Fix signal ucount refcounting")
> Tested-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> Co-debugged-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> Cc: Kees Cook <kees@xxxxxxxxxx>
> Cc: Andrei Vagin <avagin@xxxxxxxxxx>
> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> Cc: Alexey Gladkov <legion@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
> ---
> kernel/ucount.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/ucount.c b/kernel/ucount.c
> index 8c07714ff27d..16c0ea1cb432 100644
> --- a/kernel/ucount.c
> +++ b/kernel/ucount.c
> @@ -328,13 +328,12 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type)
> if (new != 1)
> continue;
> if (!get_ucounts(iter))
> - goto dec_unwind;
> + goto unwind;
> }
> return ret;
> -dec_unwind:
> +unwind:
> dec = atomic_long_sub_return(1, &iter->rlimit[type]);
> WARN_ON_ONCE(dec < 0);
> -unwind:
> do_dec_rlimit_put_ucounts(ucounts, iter, type);
> return 0;
> }
Agree. The do_dec_rlimit_put_ucounts() decreases rlimit up to iter but
does not include it.
Except for a small NAK because the patch changes goto for get_ucounts()
and not for rlimit overflow check.
Acked-by: Alexey Gladkov <legion@xxxxxxxxxx>
--
Rgrds, legion
