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 116E21422B8; Wed, 19 Jun 2024 13:14:23 +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=1718802863; cv=none; b=QFd28n3tcXSIveHcvwdKOsgD0XRBOQrRwBxuqonZx2T+Lx4GQbf1mV6WntzMQKeMOnX8mwLmh5YCd1AH/jYW9LYloRC2jXakmcE8ceN8mFv6LpSfeOkkOGGpUGUa0sKy7Dt7LI1nnkwsKr99tV/eXmZPhsvFYvBWnrgU5UjYJ8A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718802863; c=relaxed/simple; bh=lgu4kQ01zmtQXPotEc5nNiXHSMChZauOnWlH287yKQY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ss7HdPA2TFUvUP1ceVXQBwLJfHa1oq7m90uszQGG31M+Dy/HUajKVbnHOwQpwqjk79C+ICatbSbylmQM84T4FPX2IpNuyLmFgaNaVsQUlbfhA5NhQ9y5/G/aNJ3qDugwy7O+147as+4G4UAxgyLqV9+AK6+Mlaacu80wylu8PXU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=drAePVd/; 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="drAePVd/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83B8FC2BBFC; Wed, 19 Jun 2024 13:14:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718802862; bh=lgu4kQ01zmtQXPotEc5nNiXHSMChZauOnWlH287yKQY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=drAePVd/G8nklDRL3+jR39cb74huqUi87zbqsHvR0xBmmhYa8wiTLFeyfx7MpdvIA 6BgnwTT1wxYkcZchhUnbCNt6nGfPVzXuWSSbbuscI19+e5EAxhYp1+adkfXGLJk93U jR/R69wpSrwwENWwntDZOxHRwwh/MrS6pUY4Hj7o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Martin KaFai Lau , Paolo Abeni , Sasha Levin Subject: [PATCH 6.9 071/281] ipv6: fix possible race in __fib6_drop_pcpu_from() Date: Wed, 19 Jun 2024 14:53:50 +0200 Message-ID: <20240619125612.575526016@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240619125609.836313103@linuxfoundation.org> References: <20240619125609.836313103@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit b01e1c030770ff3b4fe37fc7cc6bca03f594133f ] syzbot found a race in __fib6_drop_pcpu_from() [1] If compiler reads more than once (*ppcpu_rt), second read could read NULL, if another cpu clears the value in rt6_get_pcpu_route(). Add a READ_ONCE() to prevent this race. Also add rcu_read_lock()/rcu_read_unlock() because we rely on RCU protection while dereferencing pcpu_rt. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097] CPU: 0 PID: 7543 Comm: kworker/u8:17 Not tainted 6.10.0-rc1-syzkaller-00013-g2bfcfd584ff5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Workqueue: netns cleanup_net RIP: 0010:__fib6_drop_pcpu_from.part.0+0x10a/0x370 net/ipv6/ip6_fib.c:984 Code: f8 48 c1 e8 03 80 3c 28 00 0f 85 16 02 00 00 4d 8b 3f 4d 85 ff 74 31 e8 74 a7 fa f7 49 8d bf 90 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 28 00 0f 85 1e 02 00 00 49 8b 87 90 00 00 00 48 8b 0c 24 48 RSP: 0018:ffffc900040df070 EFLAGS: 00010206 RAX: 0000000000000012 RBX: 0000000000000001 RCX: ffffffff89932e16 RDX: ffff888049dd1e00 RSI: ffffffff89932d7c RDI: 0000000000000091 RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000007 R10: 0000000000000001 R11: 0000000000000006 R12: ffff88807fa080b8 R13: fffffbfff1a9a07d R14: ffffed100ff41022 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32c26000 CR3: 000000005d56e000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __fib6_drop_pcpu_from net/ipv6/ip6_fib.c:966 [inline] fib6_drop_pcpu_from net/ipv6/ip6_fib.c:1027 [inline] fib6_purge_rt+0x7f2/0x9f0 net/ipv6/ip6_fib.c:1038 fib6_del_route net/ipv6/ip6_fib.c:1998 [inline] fib6_del+0xa70/0x17b0 net/ipv6/ip6_fib.c:2043 fib6_clean_node+0x426/0x5b0 net/ipv6/ip6_fib.c:2205 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2127 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2175 fib6_clean_tree+0xd7/0x120 net/ipv6/ip6_fib.c:2255 __fib6_clean_all+0x100/0x2d0 net/ipv6/ip6_fib.c:2271 rt6_sync_down_dev net/ipv6/route.c:4906 [inline] rt6_disable_ip+0x7ed/0xa00 net/ipv6/route.c:4911 addrconf_ifdown.isra.0+0x117/0x1b40 net/ipv6/addrconf.c:3855 addrconf_notify+0x223/0x19e0 net/ipv6/addrconf.c:3778 notifier_call_chain+0xb9/0x410 kernel/notifier.c:93 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1992 call_netdevice_notifiers_extack net/core/dev.c:2030 [inline] call_netdevice_notifiers net/core/dev.c:2044 [inline] dev_close_many+0x333/0x6a0 net/core/dev.c:1585 unregister_netdevice_many_notify+0x46d/0x19f0 net/core/dev.c:11193 unregister_netdevice_many net/core/dev.c:11276 [inline] default_device_exit_batch+0x85b/0xae0 net/core/dev.c:11759 ops_exit_list+0x128/0x180 net/core/net_namespace.c:178 cleanup_net+0x5b7/0xbf0 net/core/net_namespace.c:640 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231 process_scheduled_works kernel/workqueue.c:3312 [inline] worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Fixes: d52d3997f843 ("ipv6: Create percpu rt6_info") Signed-off-by: Eric Dumazet Cc: Martin KaFai Lau Link: https://lore.kernel.org/r/20240604193549.981839-1-edumazet@google.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/ipv6/ip6_fib.c | 6 +++++- net/ipv6/route.c | 1 + 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index c1f62352a4814..1ace4ac3ee04c 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -965,6 +965,7 @@ static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh, if (!fib6_nh->rt6i_pcpu) return; + rcu_read_lock(); /* release the reference to this fib entry from * all of its cached pcpu routes */ @@ -973,7 +974,9 @@ static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh, struct rt6_info *pcpu_rt; ppcpu_rt = per_cpu_ptr(fib6_nh->rt6i_pcpu, cpu); - pcpu_rt = *ppcpu_rt; + + /* Paired with xchg() in rt6_get_pcpu_route() */ + pcpu_rt = READ_ONCE(*ppcpu_rt); /* only dropping the 'from' reference if the cached route * is using 'match'. The cached pcpu_rt->from only changes @@ -987,6 +990,7 @@ static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh, fib6_info_release(from); } } + rcu_read_unlock(); } struct fib6_nh_pcpu_arg { diff --git a/net/ipv6/route.c b/net/ipv6/route.c index f090e7bcb784f..bca6f33c7bb9e 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1409,6 +1409,7 @@ static struct rt6_info *rt6_get_pcpu_route(const struct fib6_result *res) struct rt6_info *prev, **p; p = this_cpu_ptr(res->nh->rt6i_pcpu); + /* Paired with READ_ONCE() in __fib6_drop_pcpu_from() */ prev = xchg(p, NULL); if (prev) { dst_dev_put(&prev->dst); -- 2.43.0