netdev - [PATCH] net: ipv4: Potential null pointer dereference in cipso_v4_parsetag

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Message-ID: <20250908080315.174-1-chenyufeng@iie.ac.cn>
Date: Mon,  8 Sep 2025 16:03:15 +0800
From: Chen Yufeng <chenyufeng@....ac.cn>
To: paul@...l-moore.com
Cc: davem@...emloft.net,
	dsahern@...nel.org,
	netdev@...r.kernel.org,
	Chen Yufeng <chenyufeng@....ac.cn>
Subject: [PATCH] net: ipv4: Potential null pointer dereference in cipso_v4_parsetag_enum

While parsing CIPSO enumerated tags, secattr->flags is set to 
NETLBL_SECATTR_MLS_CAT even if secattr->attr.mls.cat is NULL.
If subsequent code attempts to access secattr->attr.mls.cat, 
it may lead to a null pointer dereference, causing a system crash.

To address this issue, we add a check to ensure that before setting
the NETLBL_SECATTR_MLS_CAT flag, secattr->attr.mls.cat is not NULL.

fixed code:
```
if (secattr->attr.mls.cat)
    secattr->flags |= NETLBL_SECATTR_MLS_CAT;
```

This patch is similar to eead1c2ea250("netlabel: cope with NULL catmap").

Signed-off-by: Chen Yufeng <chenyufeng@....ac.cn>
---
 net/ipv4/cipso_ipv4.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 740af8541d2f..2190333d78cb 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1339,8 +1339,8 @@ static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
 			netlbl_catmap_free(secattr->attr.mls.cat);
 			return ret_val;
 		}
-
-		secattr->flags |= NETLBL_SECATTR_MLS_CAT;
+		if (secattr->attr.mls.cat)
+			secattr->flags |= NETLBL_SECATTR_MLS_CAT;
 	}

 	return 0;
-- 
2.34.1