Ything-RepoMirrors/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-01-25 07:47:50 +00:00
Code Issues Packages Projects Releases Wiki Activity

rxrpc: Fix data-race warning and potential load/store tearing

Browse Source 
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: ace45bec6d ("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 <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Simon Horman <horms@kernel.org>
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 <kuba@kernel.org>
This commit is contained in:
David Howells
2026-01-20 10:13:05 +00:00
committed by Jakub Kicinski
parent 869f3f7f1f
commit 5d5fe8bcd3
7 changed files with 36 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
net/rxrpc/ar-internal.h
View File

@@ -387,7 +387,7 @@ struct rxrpc_peer {
struct rb_root service_conns; /* Service connections */
struct list_head keepalive_link; /* Link in net->peer_keepalive[] */
unsigned long app_data; /* Application data (e.g. afs_server) */
time64_t last_tx_at; /* Last time packet sent here */
unsigned int last_tx_at; /* Last time packet sent here (time64_t LSW) */
seqlock_t service_conn_lock;
spinlock_t lock; /* access lock */
int debug_id; /* debug ID for printks */
@@ -1379,6 +1379,13 @@ void rxrpc_peer_keepalive_worker(struct work_struct *);
void rxrpc_input_probe_for_pmtud(struct rxrpc_connection *conn, rxrpc_serial_t acked_serial,
bool sendmsg_fail);
/* Update the last transmission time on a peer for keepalive purposes. */
static inline void rxrpc_peer_mark_tx(struct rxrpc_peer *peer)
{
/* To avoid tearing on 32-bit systems, we only keep the LSW. */
WRITE_ONCE(peer->last_tx_at, ktime_get_seconds());
}
/*
* peer_object.c
*/

2
net/rxrpc/conn_event.c
View File

@@ -194,7 +194,7 @@ void rxrpc_conn_retransmit_call(struct rxrpc_connection *conn,
}
ret = kernel_sendmsg(conn->local->socket, &msg, iov, ioc, len);
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
if (ret < 0)
trace_rxrpc_tx_fail(chan->call_debug_id, serial, ret,
rxrpc_tx_point_call_final_resend);

14
net/rxrpc/output.c
View File

@@ -275,7 +275,7 @@ static void rxrpc_send_ack_packet(struct rxrpc_call *call, int nr_kv, size_t len
rxrpc_local_dont_fragment(conn->local, why == rxrpc_propose_ack_ping_for_mtu_probe);
ret = do_udp_sendmsg(conn->local->socket, &msg, len);
call->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(call->peer);
if (ret < 0) {
trace_rxrpc_tx_fail(call->debug_id, serial, ret,
rxrpc_tx_point_call_ack);
@@ -411,7 +411,7 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call)
iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, sizeof(pkt));
ret = do_udp_sendmsg(conn->local->socket, &msg, sizeof(pkt));
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
if (ret < 0)
trace_rxrpc_tx_fail(call->debug_id, serial, ret,
rxrpc_tx_point_call_abort);
@@ -698,7 +698,7 @@ void rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req
ret = 0;
trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags,
rxrpc_txdata_inject_loss);
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
goto done;
}
}
@@ -711,7 +711,7 @@ void rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req
*/
rxrpc_inc_stat(call->rxnet, stat_tx_data_send);
ret = do_udp_sendmsg(conn->local->socket, &msg, len);
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
if (ret == -EMSGSIZE) {
rxrpc_inc_stat(call->rxnet, stat_tx_data_send_msgsize);
@@ -797,7 +797,7 @@ void rxrpc_send_conn_abort(struct rxrpc_connection *conn)
trace_rxrpc_tx_packet(conn->debug_id, &whdr, rxrpc_tx_point_conn_abort);
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
}
/*
@@ -917,7 +917,7 @@ void rxrpc_send_keepalive(struct rxrpc_peer *peer)
trace_rxrpc_tx_packet(peer->debug_id, &whdr,
rxrpc_tx_point_version_keepalive);
peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(peer);
_leave("");
}
@@ -973,7 +973,7 @@ void rxrpc_send_response(struct rxrpc_connection *conn, struct sk_buff *response
if (ret < 0)
goto fail;
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
return;
fail:

17
net/rxrpc/peer_event.c
View File

@@ -237,6 +237,21 @@ static void rxrpc_distribute_error(struct rxrpc_peer *peer, struct sk_buff *skb,
spin_unlock_irq(&peer->lock);
}
/*
* Reconstruct the last transmission time. The difference calculated should be
* valid provided no more than ~68 years elapsed since the last transmission.
*/
static time64_t rxrpc_peer_get_tx_mark(const struct rxrpc_peer *peer, time64_t base)
{
s32 last_tx_at = READ_ONCE(peer->last_tx_at);
s32 base_lsw = base;
s32 diff = last_tx_at - base_lsw;
diff = clamp(diff, -RXRPC_KEEPALIVE_TIME, RXRPC_KEEPALIVE_TIME);
return diff + base;
}
/*
* Perform keep-alive pings.
*/
@@ -265,7 +280,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
spin_unlock_bh(&rxnet->peer_hash_lock);
if (use) {
keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
keepalive_at = rxrpc_peer_get_tx_mark(peer, base) + RXRPC_KEEPALIVE_TIME;
slot = keepalive_at - base;
_debug("%02x peer %u t=%d {%pISp}",
cursor, peer->debug_id, slot, &peer->srx.transport);

4
net/rxrpc/proc.c
View File

@@ -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));

2
net/rxrpc/rxgk.c
View File

@@ -678,7 +678,7 @@ static int rxgk_issue_challenge(struct rxrpc_connection *conn)
ret = do_udp_sendmsg(conn->local->socket, &msg, len);
if (ret > 0)
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
__free_page(page);
if (ret < 0) {

2
net/rxrpc/rxkad.c
View File

@@ -694,7 +694,7 @@ static int rxkad_issue_challenge(struct rxrpc_connection *conn)
return -EAGAIN;
}
conn->peer->last_tx_at = ktime_get_seconds();
rxrpc_peer_mark_tx(conn->peer);
trace_rxrpc_tx_packet(conn->debug_id, &whdr,
rxrpc_tx_point_rxkad_challenge);
_leave(" = 0");