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 781235F54E; Tue, 13 Feb 2024 17:25:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707845135; cv=none; b=WjQUKV9W9i2WirSZTHj7BhnAfZEHMIrPpA4jmyaSW9VqE+uPZ1Xl3mUbUMG40dyDRwp7QkYGe2sChF3HkzRNePHxGQPOlPog0axAp2Ugfi/EuMZ7PmP+KggSDFQyoImY6kje1xXsMXgDxTT3evaS4IJJ8XxBApknaP1x/IH30hs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707845135; c=relaxed/simple; bh=OkuSVXJKQ8Xdho2+St+AIbEpsSEDTgVdXEnQkaVb6K8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R4MWkO/BW7o0dRfH8+PxhoyvmQVXs15MC+YCcb/APUO9wCsF9aDxgR/HwoS2xlQLGM4uPVdu3/4cAkbj+j1Te/1vMkyJPcZSRIr+ygRXOYiY+RZ88y9mfAupyx/JunfEFPVuLhPefxSJR/gBXj69T1Vr7c1TWzLyBxj1qS9JZ2U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bw82lcXU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bw82lcXU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A639C433C7; Tue, 13 Feb 2024 17:25:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1707845135; bh=OkuSVXJKQ8Xdho2+St+AIbEpsSEDTgVdXEnQkaVb6K8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bw82lcXU9ua1wTxW4vLKoeu02bdFnD8VNRj5wk6X5cJ+uf1c71nWB8BRh9xDlfS4x VQG4blIL6n6+3LkaI/f0+34iDYrR7pBgm01oyMgWmVkSblgNLJuF3+fYP0SOVv+Awy ihsPTp6v47N9B+T+jcXszzPyBblXE+nyIA2F0Hcc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+fa3ef895554bdbfd1183@syzkaller.appspotmail.com, Kuniyuki Iwashima , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 29/64] af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC. Date: Tue, 13 Feb 2024 18:21:15 +0100 Message-ID: <20240213171845.668600346@linuxfoundation.org> X-Mailer: git-send-email 2.43.1 In-Reply-To: <20240213171844.702064831@linuxfoundation.org> References: <20240213171844.702064831@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 1279f9d9dec2d7462823a18c29ad61359e0a007d ] syzbot reported a warning [0] in __unix_gc() with a repro, which creates a socketpair and sends one socket's fd to itself using the peer. socketpair(AF_UNIX, SOCK_STREAM, 0, [3, 4]) = 0 sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\360", iov_len=1}], msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, cmsg_data=[3]}], msg_controllen=24, msg_flags=0}, MSG_OOB|MSG_PROBE|MSG_DONTWAIT|MSG_ZEROCOPY) = 1 This forms a self-cyclic reference that GC should finally untangle but does not due to lack of MSG_OOB handling, resulting in memory leak. Recently, commit 11498715f266 ("af_unix: Remove io_uring code for GC.") removed io_uring's dead code in GC and revealed the problem. The code was executed at the final stage of GC and unconditionally moved all GC candidates from gc_candidates to gc_inflight_list. That papered over the reported problem by always making the following WARN_ON_ONCE(!list_empty(&gc_candidates)) false. The problem has been there since commit 2aab4b969002 ("af_unix: fix struct pid leaks in OOB support") added full scm support for MSG_OOB while fixing another bug. To fix this problem, we must call kfree_skb() for unix_sk(sk)->oob_skb if the socket still exists in gc_candidates after purging collected skb. Then, we need to set NULL to oob_skb before calling kfree_skb() because it calls last fput() and triggers unix_release_sock(), where we call duplicate kfree_skb(u->oob_skb) if not NULL. Note that the leaked socket remained being linked to a global list, so kmemleak also could not detect it. We need to check /proc/net/protocol to notice the unfreed socket. [0]: WARNING: CPU: 0 PID: 2863 at net/unix/garbage.c:345 __unix_gc+0xc74/0xe80 net/unix/garbage.c:345 Modules linked in: CPU: 0 PID: 2863 Comm: kworker/u4:11 Not tainted 6.8.0-rc1-syzkaller-00583-g1701940b1a02 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Workqueue: events_unbound __unix_gc RIP: 0010:__unix_gc+0xc74/0xe80 net/unix/garbage.c:345 Code: 8b 5c 24 50 e9 86 f8 ff ff e8 f8 e4 22 f8 31 d2 48 c7 c6 30 6a 69 89 4c 89 ef e8 97 ef ff ff e9 80 f9 ff ff e8 dd e4 22 f8 90 <0f> 0b 90 e9 7b fd ff ff 48 89 df e8 5c e7 7c f8 e9 d3 f8 ff ff e8 RSP: 0018:ffffc9000b03fba0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffc9000b03fc10 RCX: ffffffff816c493e RDX: ffff88802c02d940 RSI: ffffffff896982f3 RDI: ffffc9000b03fb30 RBP: ffffc9000b03fce0 R08: 0000000000000001 R09: fffff52001607f66 R10: 0000000000000003 R11: 0000000000000002 R12: dffffc0000000000 R13: ffffc9000b03fc10 R14: ffffc9000b03fc10 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005559c8677a60 CR3: 000000000d57a000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: process_one_work+0x889/0x15e0 kernel/workqueue.c:2633 process_scheduled_works kernel/workqueue.c:2706 [inline] worker_thread+0x8b9/0x12a0 kernel/workqueue.c:2787 kthread+0x2c6/0x3b0 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 Reported-by: syzbot+fa3ef895554bdbfd1183@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fa3ef895554bdbfd1183 Fixes: 2aab4b969002 ("af_unix: fix struct pid leaks in OOB support") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240203183149.63573-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/unix/garbage.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/unix/garbage.c b/net/unix/garbage.c index dc2763540393..767b338a7a2d 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -314,6 +314,17 @@ void unix_gc(void) /* Here we are. Hitlist is filled. Die. */ __skb_queue_purge(&hitlist); +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + list_for_each_entry_safe(u, next, &gc_candidates, link) { + struct sk_buff *skb = u->oob_skb; + + if (skb) { + u->oob_skb = NULL; + kfree_skb(skb); + } + } +#endif + spin_lock(&unix_gc_lock); /* There could be io_uring registered files, just push them back to -- 2.43.0