[PATCH] ucounts: fix counter leak in inc_rlimit_get_ucounts()

[Andrei Vagin <avagin@google.com>]

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@linux.dev>
Co-debugged-by: Roman Gushchin <roman.gushchin@linux.dev>
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: <stable@vger.kernel.org>
Signed-off-by: Andrei Vagin <avagin@google.com>
---
 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;
 }
-- 
2.47.0.163.g1226f6d8fa-goog