From e9293fd04c1b521011c312cfe0bf4545a2c22157 Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Mon, 21 Jul 2025 19:45:57 +0200 Subject: [PATCH] ucount: fix atomic_long_inc_below() argument type MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit f8cd9193b62e92ad25def5370ca8ea2bc7585381 ] The type of u argument of atomic_long_inc_below() should be long to avoid unwanted truncation to int. The patch fixes the wrong argument type of an internal function to prevent unwanted argument truncation. It fixes an internal locking primitive; it should not have any direct effect on userspace. Mark said : AFAICT there's no problem in practice because atomic_long_inc_below() : is only used by inc_ucount(), and it looks like the value is : constrained between 0 and INT_MAX. : : In inc_ucount() the limit value is taken from : user_namespace::ucount_max[], and AFAICT that's only written by : sysctls, to the table setup by setup_userns_sysctls(), where : UCOUNT_ENTRY() limits the value between 0 and INT_MAX. : : This is certainly a cleanup, but there might be no functional issue in : practice as above. Link: https://lkml.kernel.org/r/20250721174610.28361-1-ubizjak@gmail.com Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t") Signed-off-by: Uros Bizjak Reviewed-by: "Eric W. Biederman" Cc: Sebastian Andrzej Siewior Cc: "Paul E. McKenney" Cc: Alexey Gladkov Cc: Roman Gushchin Cc: MengEn Sun Cc: "Thomas Weißschuh" Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/ucount.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/ucount.c b/kernel/ucount.c index 85d7c19b0b80..8c21398f7b4f 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -210,7 +210,7 @@ void put_ucounts(struct ucounts *ucounts) } } -static inline bool atomic_long_inc_below(atomic_long_t *v, int u) +static inline bool atomic_long_inc_below(atomic_long_t *v, long u) { long c, old; c = atomic_long_read(v);