lkml.org 
[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.15 195/262] mptcp: Correctly set DATA_FIN timeout when number of retransmits is large
Date
From: Mat Martineau <mathew.j.martineau@linux.intel.com>

commit 877d11f0332cd2160e19e3313e262754c321fa36 upstream.

Syzkaller with UBSAN uncovered a scenario where a large number of
DATA_FIN retransmits caused a shift-out-of-bounds in the DATA_FIN
timeout calculation:

================================================================================
UBSAN: shift-out-of-bounds in net/mptcp/protocol.c:470:29
shift exponent 32 is too large for 32-bit type 'unsigned int'
CPU: 1 PID: 13059 Comm: kworker/1:0 Not tainted 5.17.0-rc2-00630-g5fbf21c90c60 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Workqueue: events mptcp_worker
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
ubsan_epilogue+0xb/0x5a lib/ubsan.c:151
__ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e lib/ubsan.c:330
mptcp_set_datafin_timeout net/mptcp/protocol.c:470 [inline]
__mptcp_retrans.cold+0x72/0x77 net/mptcp/protocol.c:2445
mptcp_worker+0x58a/0xa70 net/mptcp/protocol.c:2528
process_one_work+0x9df/0x16d0 kernel/workqueue.c:2307
worker_thread+0x95/0xe10 kernel/workqueue.c:2454
kthread+0x2f4/0x3b0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
================================================================================

This change limits the maximum timeout by limiting the size of the
shift, which keeps all intermediate values in-bounds.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/259
Fixes: 6477dd39e62c ("mptcp: Retransmit DATA_FIN")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mptcp/protocol.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -406,9 +406,12 @@ static bool mptcp_pending_data_fin(struc
static void mptcp_set_datafin_timeout(const struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
+ u32 retransmits;

- mptcp_sk(sk)->timer_ival = min(TCP_RTO_MAX,
- TCP_RTO_MIN << icsk->icsk_retransmits);
+ retransmits = min_t(u32, icsk->icsk_retransmits,
+ ilog2(TCP_RTO_MAX / TCP_RTO_MIN));
+
+ mptcp_sk(sk)->timer_ival = TCP_RTO_MIN << retransmits;
}

static void __mptcp_set_timeout(struct sock *sk, long tout)

\
 
 \ /
  Last update: 2022-03-07 11:14    [W:0.907 / U:0.280 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site