diff mbox series

[net,3/9] mptcp: fix memory accounting on allocation error

Message ID 20210304213216.205472-4-mathew.j.martineau@linux.intel.com (mailing list archive)
State Accepted
Commit eaeef1ce55ec9161e0c44ff27017777b1644b421
Delegated to: Netdev Maintainers
Headers show
Series mptcp: Fixes for v5.12 | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net
netdev/subject_prefix success Link
netdev/cc_maintainers fail 1 blamed authors not CCed: fw@strlen.de; 1 maintainers not CCed: fw@strlen.de
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 2 this patch: 2
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 7 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Mat Martineau March 4, 2021, 9:32 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

In case of memory pressure the MPTCP xmit path keeps
at most a single skb in the tx cache, eventually freeing
additional ones.

The associated counter for forward memory is not update
accordingly, and that causes the following splat:

WARNING: CPU: 0 PID: 12 at net/core/stream.c:208 sk_stream_kill_queues+0x3ca/0x530 net/core/stream.c:208
Modules linked in:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.11.0-rc2 #59
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Workqueue: events mptcp_worker
RIP: 0010:sk_stream_kill_queues+0x3ca/0x530 net/core/stream.c:208
Code: 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 63 01 00 00 8b ab 00 01 00 00 e9 60 ff ff ff e8 2f 24 d3 fe 0f 0b eb 97 e8 26 24 d3 fe <0f> 0b eb a0 e8 1d 24 d3 fe 0f 0b e9 a5 fe ff ff 4c 89 e7 e8 0e d0
RSP: 0018:ffffc900000c7bc8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88810030ac40 RSI: ffffffff8262ca4a RDI: 0000000000000003
RBP: 0000000000000d00 R08: 0000000000000000 R09: ffffffff85095aa7
R10: ffffffff8262c9ea R11: 0000000000000001 R12: ffff888108908100
R13: ffffffff85095aa0 R14: ffffc900000c7c48 R15: 1ffff92000018f85
FS:  0000000000000000(0000) GS:ffff88811b200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa7444baef8 CR3: 0000000035ee9005 CR4: 0000000000170ef0
Call Trace:
 __mptcp_destroy_sock+0x4a7/0x6c0 net/mptcp/protocol.c:2547
 mptcp_worker+0x7dd/0x1610 net/mptcp/protocol.c:2272
 process_one_work+0x896/0x1170 kernel/workqueue.c:2275
 worker_thread+0x605/0x1350 kernel/workqueue.c:2421
 kthread+0x344/0x410 kernel/kthread.c:292
 ret_from_fork+0x22/0x30 arch/x86/entry/entry_64.S:296

At close time, as reported by syzkaller/Christoph.

This change address the issue properly updating the fwd
allocated memory counter in the error path.

Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/136
Fixes: 724cfd2ee8aa ("mptcp: allocate TX skbs in msk context")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 7362a536cbc0..aa59101ffe54 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1189,6 +1189,7 @@  static bool mptcp_tx_cache_refill(struct sock *sk, int size,
 			 */
 			while (skbs->qlen > 1) {
 				skb = __skb_dequeue_tail(skbs);
+				*total_ts -= skb->truesize;
 				__kfree_skb(skb);
 			}
 			return skbs->qlen > 0;