[PATCH 5.10] netfilter: nft_socket: fix sk refcount leaks

[PATCH 5.10] netfilter: nft_socket: fix sk refcount leaks

[Denis Arefev]

From: Florian Westphal <fw@strlen.de>             

commit 8b26ff7af8c32cb4148b3e147c52f9e4c695209c upstream.

We must put 'sk' reference before returning.

Fixes: 039b1f4f24ec ("netfilter: nft_socket: fix erroneous socket assignment")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[Denis: minor fix to resolve merge conflict.]  
Signed-off-by: Denis Arefev <arefev@swemel.ru> 
---
Backport fix for CVE-2024-46855
Link: https://nvd.nist.gov/vuln/detail/CVE-2024-46855
---
 net/netfilter/nft_socket.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c
index 826e5f8c78f3..07e73e50b713 100644
--- a/net/netfilter/nft_socket.c
+++ b/net/netfilter/nft_socket.c
@@ -88,13 +88,13 @@ static void nft_socket_eval(const struct nft_expr *expr,
 			*dest = sk->sk_mark;
 		} else {
 			regs->verdict.code = NFT_BREAK;
-			return;
+			goto out_put_sk;
 		}
 		break;
 	case NFT_SOCKET_WILDCARD:
 		if (!sk_fullsock(sk)) {
 			regs->verdict.code = NFT_BREAK;
-			return;
+			goto out_put_sk;
 		}
 		nft_socket_wildcard(pkt, regs, sk, dest);
 		break;
@@ -103,6 +103,7 @@ static void nft_socket_eval(const struct nft_expr *expr,
 		regs->verdict.code = NFT_BREAK;
 	}
 
+out_put_sk:
 	if (sk != skb->sk)
 		sock_gen_put(sk);
 }
-- 
2.43.0

Re: [PATCH 5.10] netfilter: nft_socket: fix sk refcount leaks

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 8b26ff7af8c32cb4148b3e147c52f9e4c695209c

WARNING: Author mismatch between patch and upstream commit:
Backport author: Denis Arefev<arefev@swemel.ru>
Commit author: Florian Westphal<fw@strlen.de>

Status in newer kernel trees:
6.15.y | Present (exact SHA1)
6.14.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: 83e6fb59040e)
6.1.y | Present (different SHA1: 33c2258bf8cb)
5.15.y | Present (different SHA1: ddc7c423c4a5)

Note: The patch differs from the upstream commit:
---
1:  8b26ff7af8c32 ! 1:  a2677efdc7b71 netfilter: nft_socket: fix sk refcount leaks
    @@ Metadata
      ## Commit message ##
         netfilter: nft_socket: fix sk refcount leaks
     
    +    commit 8b26ff7af8c32cb4148b3e147c52f9e4c695209c upstream.
    +
         We must put 'sk' reference before returning.
     
         Fixes: 039b1f4f24ec ("netfilter: nft_socket: fix erroneous socket assignment")
         Signed-off-by: Florian Westphal <fw@strlen.de>
         Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    +    [Denis: minor fix to resolve merge conflict.]
    +    Signed-off-by: Denis Arefev <arefev@swemel.ru>
     
      ## net/netfilter/nft_socket.c ##
     @@ net/netfilter/nft_socket.c: static void nft_socket_eval(const struct nft_expr *expr,
    - 			*dest = READ_ONCE(sk->sk_mark);
    + 			*dest = sk->sk_mark;
      		} else {
      			regs->verdict.code = NFT_BREAK;
     -			return;
    @@ net/netfilter/nft_socket.c: static void nft_socket_eval(const struct nft_expr *e
      		}
      		nft_socket_wildcard(pkt, regs, sk, dest);
      		break;
    -@@ net/netfilter/nft_socket.c: static void nft_socket_eval(const struct nft_expr *expr,
    - 	case NFT_SOCKET_CGROUPV2:
    - 		if (!nft_sock_get_eval_cgroupv2(dest, sk, pkt, priv->level)) {
    - 			regs->verdict.code = NFT_BREAK;
    --			return;
    -+			goto out_put_sk;
    - 		}
    - 		break;
    - #endif
     @@ net/netfilter/nft_socket.c: static void nft_socket_eval(const struct nft_expr *expr,
      		regs->verdict.code = NFT_BREAK;
      	}
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.10.y       |  Success    |  Success   |

Re: [PATCH 5.10] netfilter: nft_socket: fix sk refcount leaks

[Pablo Neira Ayuso]

On Mon, Jun 02, 2025 at 03:39:47PM +0300, Denis Arefev wrote:
> From: Florian Westphal <fw@strlen.de>             
> 
> commit 8b26ff7af8c32cb4148b3e147c52f9e4c695209c upstream.
> 
> We must put 'sk' reference before returning.

I have a backport for 5.4 in the queue, I will take care of this.

Thanks.