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[5/8] ucounts: Handle wrapping in is_ucounts_overlimit

Message ID 20220211021324.4116773-5-ebiederm@xmission.com
State Accepted
Commit 0cbae9e24fa7d6c6e9f828562f084da82217a0c5
Headers show
Series [1/8] ucounts: Fix RLIMIT_NPROC regression | expand

Commit Message

Eric W. Biederman Feb. 11, 2022, 2:13 a.m. UTC
While examining is_ucounts_overlimit and reading the various messages
I realized that is_ucounts_overlimit fails to deal with counts that
may have wrapped.

Being wrapped should be a transitory state for counts and they should
never be wrapped for long, but it can happen so handle it.

Cc: stable@vger.kernel.org
Fixes: 21d1c5e386bc ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/ucount.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/kernel/ucount.c b/kernel/ucount.c
index 65b597431c86..06ea04d44685 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -350,7 +350,8 @@  bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsign
 	if (rlimit > LONG_MAX)
 		max = LONG_MAX;
 	for (iter = ucounts; iter; iter = iter->ns->ucounts) {
-		if (get_ucounts_value(iter, type) > max)
+		long val = get_ucounts_value(iter, type);
+		if (val < 0 || val > max)
 			return true;
 		max = READ_ONCE(iter->ns->ucount_max[type]);
 	}