diff options
| author | Mat Martineau <mathew.j.martineau@linux.intel.com> | 2022-02-24 16:52:59 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-02-24 21:54:54 -0800 |
| commit | 877d11f0332cd2160e19e3313e262754c321fa36 (patch) | |
| tree | b0bed94f83ecfdce733388722afcee8d0a52ea42 /net | |
| parent | 63bb8239d80571204c61d19c73f7bf5e3d9ef5fa (diff) | |
mptcp: Correctly set DATA_FIN timeout when number of retransmits is large
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/mptcp/protocol.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 12bb28c5007e..1c72f25f083e 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -466,9 +466,12 @@ static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq) 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) |