From nobody Wed Apr 8 01:16:36 2026 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E0FA3783DA for ; Wed, 11 Mar 2026 07:06:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773212796; cv=none; b=McuEyRkuNpCysdruhHl0P6ZDtAg9IWW+T6mJ5NvoIPyXgG+ZVAy+0vD0F3AGqxaKq/MelCE/chgkqKclOAr1BB2fhl4mxAt9HaIgbt0F5J1Ax55oTE5x606gSRMMEVJE6w88Yt7aYmdkD4PN4ZIIQSOO3Anm1Oe3f8ajUp1+pDw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773212796; c=relaxed/simple; bh=fDoXbQjgWEGw9tvqtPVdOHqQWf6S2QPStECJ9pYJGnM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=qHZNkrDaxLdOov8wpmkadZcb+HzbNVNK1nFAIV2D6KpZzzk+FQ8KNMp4QkJn2DzB1mTFpDa/+YyDenT+zHfQoranYxBELDTWrtNpA1KfSd5x9uBRMd7GGIyURoMDicttpGgVGNQjsS3JjKRG34qabQWqNgA0pJQEmYrqLwB9Nyc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=eYDsJlyA; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="eYDsJlyA" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773212783; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=0CXo0x7BiCEEpnzU+2Ow+NXjhaBWC/PdinzAYFVwnT4=; b=eYDsJlyAQL5W9YiEJCWmAM0miLOaFxYlN6EA8vgkobqFWoM5Hf6U7hq/EPjdZBaO/oxRWv tuTLvtBNIszAb22CuEUHpUJ680fdStt3f8/3/2MnOXaDqTK3cEoY6Jy3RzqUupUlOkJ0V+ XWrd1wgl15XdhwgnIrdmOws3hrfxc70= From: Jiayuan Chen To: netdev@vger.kernel.org Cc: Jiayuan Chen , syzbot+d00f90e0af54102fb271@syzkaller.appspotmail.com, Eric Dumazet , Jiayuan Chen , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Kees Cook , Takamitsu Iwai , Thomas Gleixner , Pwnverse , Ingo Molnar , linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v2] net/rose: fix NULL pointer dereference in rose_transmit_link on reconnect Date: Wed, 11 Mar 2026 15:06:02 +0800 Message-ID: <20260311070611.76913-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Jiayuan Chen syzkaller reported a bug [1], and the reproducer is available at [2]. ROSE sockets use four sk->sk_state values: TCP_CLOSE, TCP_LISTEN, TCP_SYN_SENT, and TCP_ESTABLISHED. rose_connect() already rejects calls for TCP_ESTABLISHED (-EISCONN) and TCP_CLOSE with SS_CONNECTING (-ECONNREFUSED), but lacks a check for TCP_SYN_SENT. When rose_connect() is called a second time while the first connection attempt is still in progress (TCP_SYN_SENT), it overwrites rose->neighbour via rose_get_neigh(). If that returns NULL, the socket is left with rose->state =3D=3D ROSE_STATE_1 but rose->neighbour =3D=3D NUL= L. When the socket is subsequently closed, rose_release() sees ROSE_STATE_1 and calls rose_write_internal() -> rose_transmit_link(skb, NULL), causing a NULL pointer dereference. Per connect(2), a second connect() while a connection is already in progress should return -EALREADY. Add this missing check for TCP_SYN_SENT to complete the state validation in rose_connect(). [1] https://syzkaller.appspot.com/bug?extid=3Dd00f90e0af54102fb271 [2] https://gist.github.com/mrpre/9e6779e0d13e2c66779b1653fef80516 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+d00f90e0af54102fb271@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69694d6f.050a0220.58bed.0027.GAE@google= .com/T/ Suggested-by: Eric Dumazet Cc: Jiayuan Chen Signed-off-by: Jiayuan Chen Reviewed-by: Eric Dumazet --- net/rose/af_rose.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 841d62481048..ba56213e0a2a 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -811,6 +811,11 @@ static int rose_connect(struct socket *sock, struct so= ckaddr_unsized *uaddr, int goto out_release; } =20 + if (sk->sk_state =3D=3D TCP_SYN_SENT) { + err =3D -EALREADY; + goto out_release; + } + sk->sk_state =3D TCP_CLOSE; sock->state =3D SS_UNCONNECTED; =20 --=20 2.43.0