From 5d5fe8bcd331f1e34e0943ec7c18432edfcf0e8b Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 20 Jan 2026 10:13:05 +0000 Subject: rxrpc: Fix data-race warning and potential load/store tearing Fix the following: BUG: KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet which is reporting an issue with the reads and writes to ->last_tx_at in: conn->peer->last_tx_at = ktime_get_seconds(); and: keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME; The lockless accesses to these to values aren't actually a problem as the read only needs an approximate time of last transmission for the purposes of deciding whether or not the transmission of a keepalive packet is warranted yet. Also, as ->last_tx_at is a 64-bit value, tearing can occur on a 32-bit arch. Fix both of these by switching to an unsigned int for ->last_tx_at and only storing the LSW of the time64_t. It can then be reconstructed at need provided no more than 68 years has elapsed since the last transmission. Fixes: ace45bec6d77 ("rxrpc: Fix firewall route keepalive") Reported-by: syzbot+6182afad5045e6703b3d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/695e7cfb.050a0220.1c677c.036b.GAE@google.com/ Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/1107124.1768903985@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski --- net/rxrpc/proc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/rxrpc/proc.c') diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c index d803562ca0ac..59292f7f9205 100644 --- a/net/rxrpc/proc.c +++ b/net/rxrpc/proc.c @@ -296,13 +296,13 @@ static int rxrpc_peer_seq_show(struct seq_file *seq, void *v) now = ktime_get_seconds(); seq_printf(seq, - "UDP %-47.47s %-47.47s %3u %4u %5u %6llus %8d %8d\n", + "UDP %-47.47s %-47.47s %3u %4u %5u %6ds %8d %8d\n", lbuff, rbuff, refcount_read(&peer->ref), peer->cong_ssthresh, peer->max_data, - now - peer->last_tx_at, + (s32)now - (s32)READ_ONCE(peer->last_tx_at), READ_ONCE(peer->recent_srtt_us), READ_ONCE(peer->recent_rto_us)); -- cgit v1.2.3