From: Jakub Kicinski <kuba@xxxxxxxxxx>
commit f3221361dc85d4de22586ce8441ec2c67b454f5d upstream.
syzbot sent a hung task report and Eric explains that adversarial
receiver may keep RWIN at 0 for a long time, so we are not guaranteed
to make forward progress. Thread which took tx_lock and went to sleep
may not release tx_lock for hours. Use interruptible sleep where
possible and reschedule the work if it can't take the lock.
Testing: existing selftest passes
Reported-by: syzbot+9c0268252b8ef967c62e@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 79ffe6087e91 ("net/tls: add a TX lock")
Link: https://lore.kernel.org/all/000000000000e412e905f5b46201@xxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx # wait 4 weeks
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230301002857.2101894-1-kuba@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/tls/tls_sw.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -949,7 +949,9 @@ int tls_sw_sendmsg(struct sock *sk, stru
MSG_CMSG_COMPAT))
return -EOPNOTSUPP;
- mutex_lock(&tls_ctx->tx_lock);
+ ret = mutex_lock_interruptible(&tls_ctx->tx_lock);
+ if (ret)
+ return ret;
lock_sock(sk);
if (unlikely(msg->msg_controllen)) {
@@ -1283,7 +1285,9 @@ int tls_sw_sendpage(struct sock *sk, str
MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
return -EOPNOTSUPP;
- mutex_lock(&tls_ctx->tx_lock);
+ ret = mutex_lock_interruptible(&tls_ctx->tx_lock);
+ if (ret)
+ return ret;
lock_sock(sk);
ret = tls_sw_do_sendpage(sk, page, offset, size, flags);
release_sock(sk);
@@ -2266,11 +2270,19 @@ static void tx_work_handler(struct work_
if (!test_and_clear_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask))
return;
- mutex_lock(&tls_ctx->tx_lock);
- lock_sock(sk);
- tls_tx_records(sk, -1);
- release_sock(sk);
- mutex_unlock(&tls_ctx->tx_lock);
+
+ if (mutex_trylock(&tls_ctx->tx_lock)) {
+ lock_sock(sk);
+ tls_tx_records(sk, -1);
+ release_sock(sk);
+ mutex_unlock(&tls_ctx->tx_lock);
+ } else if (!test_and_set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask)) {
+ /* Someone is holding the tx_lock, they will likely run Tx
+ * and cancel the work on their way out of the lock section.
+ * Schedule a long delay just in case.
+ */
+ schedule_delayed_work(&ctx->tx_work.work, msecs_to_jiffies(10));
+ }
}
void tls_sw_write_space(struct sock *sk, struct tls_context *ctx)
