linux-kernel - [PATCH v2 net-next] net: Silence use after free static checker warning

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z8alMHz89jH3uPJ9@stanley.mountain>
Date: Tue, 4 Mar 2025 10:01:04 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ahmed Zaki <ahmed.zaki@...el.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Alexander Lobakin <aleksander.lobakin@...el.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH v2 net-next] net: Silence use after free static checker
 warning

The cpu_rmap_put() will call kfree() when the last reference is dropped.

Fortunately, this is not the the last reference so it won't free it
here.  Unfortunately, static checkers are not clever enough and they
still warn that this could lead to a use after free on the next line.
Flip these two statements around to silence the static checker false
positve.

Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 9189c4a048d7..c102349e04ee 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7072,8 +7072,8 @@ void netif_napi_set_irq_locked(struct napi_struct *napi, int irq)
 put_rmap:
 #ifdef CONFIG_RFS_ACCEL
 	if (napi->dev->rx_cpu_rmap_auto) {
-		cpu_rmap_put(napi->dev->rx_cpu_rmap);
 		napi->dev->rx_cpu_rmap->obj[napi->napi_rmap_idx] = NULL;
+		cpu_rmap_put(napi->dev->rx_cpu_rmap);
 		napi->napi_rmap_idx = -1;
 	}
 #endif
-- 
2.47.2