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ucounts: fix counter leak in inc_rlimit_get_ucounts()

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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.

Link: https://lkml.kernel.org/r/20241101191940.3211128-1-roman.gushchin@linux.dev
Fixes: 15bc01effe ("ucounts: Fix signal ucount refcounting")
Signed-off-by: Andrei Vagin <avagin@google.com>
Co-developed-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Tested-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Alexey Gladkov <legion@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Andrei Vagin <avagin@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrei Vagin 2024-11-01 19:19:40 +00:00 committed by Andrew Morton
parent 0268d45799
commit 432dc0654c
1 changed files with 1 additions and 2 deletions
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3
kernel/ucount.c
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@ -317,7 +317,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type)
for (iter = ucounts; iter; iter = iter->ns->ucounts) {
long new = atomic_long_add_return(1, &iter->rlimit[type]);
if (new < 0 || new > max)
goto unwind;
goto dec_unwind;
if (iter == ucounts)
ret = new;
max = get_userns_rlimit_max(iter->ns, type);
@ -334,7 +334,6 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum rlimit_type type)
dec_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;
}