From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4F83F15CAE for ; Tue, 8 Nov 2022 14:03:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB908C433D6; Tue, 8 Nov 2022 14:03:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667916224; bh=QiqluafjqolUkYl3jFiPP+gAdOgI1pzM/I+yc5TFvdo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qio/p5Gd4g2+CzcAbxb22H0ABwleLN3OIHHBHYNuwZixDXRKquSv0ba+zuWmV0vSe xGl+aFpEoYOusI11vUweumYfkG8L0f+T2ZPLOZqMK4hlsozoDsGeCpuBql7qERWnGP Y66Wvy5QQedE65AZhmENE9MNbqPYvUks3+tMHRt0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Kuniyuki Iwashima , "David S. Miller" , Anil Altinay Subject: [PATCH 5.15 099/144] af_unix: Fix memory leaks of the whole sk due to OOB skb. Date: Tue, 8 Nov 2022 14:39:36 +0100 Message-Id: <20221108133349.482630545@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221108133345.346704162@linuxfoundation.org> References: <20221108133345.346704162@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Kuniyuki Iwashima commit 7a62ed61367b8fd01bae1e18e30602c25060d824 upstream. syzbot reported a sequence of memory leaks, and one of them indicated we failed to free a whole sk: unreferenced object 0xffff8880126e0000 (size 1088): comm "syz-executor419", pid 326, jiffies 4294773607 (age 12.609s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 7d 00 00 00 00 00 00 00 ........}....... 01 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<000000006fefe750>] sk_prot_alloc+0x64/0x2a0 net/core/sock.c:1970 [<0000000074006db5>] sk_alloc+0x3b/0x800 net/core/sock.c:2029 [<00000000728cd434>] unix_create1+0xaf/0x920 net/unix/af_unix.c:928 [<00000000a279a139>] unix_create+0x113/0x1d0 net/unix/af_unix.c:997 [<0000000068259812>] __sock_create+0x2ab/0x550 net/socket.c:1516 [<00000000da1521e1>] sock_create net/socket.c:1566 [inline] [<00000000da1521e1>] __sys_socketpair+0x1a8/0x550 net/socket.c:1698 [<000000007ab259e1>] __do_sys_socketpair net/socket.c:1751 [inline] [<000000007ab259e1>] __se_sys_socketpair net/socket.c:1748 [inline] [<000000007ab259e1>] __x64_sys_socketpair+0x97/0x100 net/socket.c:1748 [<000000007dedddc1>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<000000007dedddc1>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<000000009456679f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd We can reproduce this issue by creating two AF_UNIX SOCK_STREAM sockets, send()ing an OOB skb to each other, and close()ing them without consuming the OOB skbs. int skpair[2]; socketpair(AF_UNIX, SOCK_STREAM, 0, skpair); send(skpair[0], "x", 1, MSG_OOB); send(skpair[1], "x", 1, MSG_OOB); close(skpair[0]); close(skpair[1]); Currently, we free an OOB skb in unix_sock_destructor() which is called via __sk_free(), but it's too late because the receiver's unix_sk(sk)->oob_skb is accounted against the sender's sk->sk_wmem_alloc and __sk_free() is called only when sk->sk_wmem_alloc is 0. In the repro sequences, we do not consume the OOB skb, so both two sk's sock_put() never reach __sk_free() due to the positive sk->sk_wmem_alloc. Then, no one can consume the OOB skb nor call __sk_free(), and we finally leak the two whole sk. Thus, we must free the unconsumed OOB skb earlier when close()ing the socket. Fixes: 314001f0bf92 ("af_unix: Add OOB support") Reported-by: syzbot Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Anil Altinay Signed-off-by: Greg Kroah-Hartman --- net/unix/af_unix.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -504,12 +504,6 @@ static void unix_sock_destructor(struct skb_queue_purge(&sk->sk_receive_queue); -#if IS_ENABLED(CONFIG_AF_UNIX_OOB) - if (u->oob_skb) { - kfree_skb(u->oob_skb); - u->oob_skb = NULL; - } -#endif WARN_ON(refcount_read(&sk->sk_wmem_alloc)); WARN_ON(!sk_unhashed(sk)); WARN_ON(sk->sk_socket); @@ -556,6 +550,13 @@ static void unix_release_sock(struct soc unix_state_unlock(sk); +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + if (u->oob_skb) { + kfree_skb(u->oob_skb); + u->oob_skb = NULL; + } +#endif + wake_up_interruptible_all(&u->peer_wait); if (skpair != NULL) {