From: David Howells <dhowells@redhat.com>
To: netdev@vger.kernel.org
Cc: syzbot+174de899852504e4a74a@syzkaller.appspotmail.com,
syzbot+3d1c772efafd3c38d007@syzkaller.appspotmail.com,
Hillf Danton <hdanton@sina.com>,
dhowells@redhat.com, linux-afs@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH net] rxrpc: Fix clearance of Tx/Rx ring when releasing a call
Date: Wed, 03 Feb 2021 08:47:56 +0000 [thread overview]
Message-ID: <161234207610.653119.5287360098400436976.stgit@warthog.procyon.org.uk> (raw)
At the end of rxrpc_release_call(), rxrpc_cleanup_ring() is called to clear
the Rx/Tx skbuff ring, but this doesn't lock the ring whilst it's accessing
it. Unfortunately, rxrpc_resend() might be trying to retransmit a packet
concurrently with this - and whilst it does lock the ring, this isn't
protection against rxrpc_cleanup_call().
Fix this by removing the call to rxrpc_cleanup_ring() from
rxrpc_release_call(). rxrpc_cleanup_ring() will be called again anyway
from rxrpc_cleanup_call(). The earlier call is just an optimisation to
recycle skbuffs more quickly.
Alternative solutions include rxrpc_release_call() could try to cancel the
work item or wait for it to complete or rxrpc_cleanup_ring() could lock
when accessing the ring (which would require a bh lock).
This can produce a report like the following:
BUG: KASAN: use-after-free in rxrpc_send_data_packet+0x19b4/0x1e70 net/rxrpc/output.c:372
Read of size 4 at addr ffff888011606e04 by task kworker/0:0/5
...
Workqueue: krxrpcd rxrpc_process_call
Call Trace:
...
kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
rxrpc_send_data_packet+0x19b4/0x1e70 net/rxrpc/output.c:372
rxrpc_resend net/rxrpc/call_event.c:266 [inline]
rxrpc_process_call+0x1634/0x1f60 net/rxrpc/call_event.c:412
process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275
...
Allocated by task 2318:
...
sock_alloc_send_pskb+0x793/0x920 net/core/sock.c:2348
rxrpc_send_data+0xb51/0x2bf0 net/rxrpc/sendmsg.c:358
rxrpc_do_sendmsg+0xc03/0x1350 net/rxrpc/sendmsg.c:744
rxrpc_sendmsg+0x420/0x630 net/rxrpc/af_rxrpc.c:560
...
Freed by task 2318:
...
kfree_skb+0x140/0x3f0 net/core/skbuff.c:704
rxrpc_free_skb+0x11d/0x150 net/rxrpc/skbuff.c:78
rxrpc_cleanup_ring net/rxrpc/call_object.c:485 [inline]
rxrpc_release_call+0x5dd/0x860 net/rxrpc/call_object.c:552
rxrpc_release_calls_on_socket+0x21c/0x300 net/rxrpc/call_object.c:579
rxrpc_release_sock net/rxrpc/af_rxrpc.c:885 [inline]
rxrpc_release+0x263/0x5a0 net/rxrpc/af_rxrpc.c:916
__sock_release+0xcd/0x280 net/socket.c:597
...
The buggy address belongs to the object at ffff888011606dc0
which belongs to the cache skbuff_head_cache of size 232
Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Reported-by: syzbot+174de899852504e4a74a@syzkaller.appspotmail.com
Reported-by: syzbot+3d1c772efafd3c38d007@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hillf Danton <hdanton@sina.com>
---
net/rxrpc/call_object.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index c845594b663f..4eb91d958a48 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -548,8 +548,6 @@ void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call)
rxrpc_disconnect_call(call);
if (call->security)
call->security->free_call_crypto(call);
-
- rxrpc_cleanup_ring(call);
_leave("");
}
next reply other threads:[~2021-02-03 8:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 8:47 David Howells [this message]
2021-02-05 2:20 ` [PATCH net] rxrpc: Fix clearance of Tx/Rx ring when releasing a call patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=161234207610.653119.5287360098400436976.stgit@warthog.procyon.org.uk \
--to=dhowells@redhat.com \
--cc=hdanton@sina.com \
--cc=linux-afs@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=syzbot+174de899852504e4a74a@syzkaller.appspotmail.com \
--cc=syzbot+3d1c772efafd3c38d007@syzkaller.appspotmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).