| Message ID | 20220225005259.318898-4-mathew.j.martineau@linux.intel.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 877d11f0332cd2160e19e3313e262754c321fa36 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | mptcp: Fixes for 5.17 | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Clearly marked for net |
| netdev/fixes_present | success | Fixes tag present in non-next series |
| netdev/subject_prefix | success | Link |
| netdev/cover_letter | success | Series has a cover letter |
| netdev/patch_count | success | Link |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 3 this patch: 3 |
| netdev/cc_maintainers | success | CCed 7 of 7 maintainers |
| netdev/build_clang | success | Errors and warnings before: 18 this patch: 18 |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/verify_fixes | success | Fixes tag looks correct |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 8 this patch: 8 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 14 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
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)
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> --- net/mptcp/protocol.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)