diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2023-02-28 16:28:57 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-03-01 20:32:36 -0800 |
| commit | f3221361dc85d4de22586ce8441ec2c67b454f5d (patch) | |
| tree | b4dbd98afdac7a8e2c5a1bc7d1f168962d6a357f | |
| parent | 49c47cc21b5b7a3d8deb18fc57b0aa2ab1286962 (diff) | |
| download | lwn-f3221361dc85d4de22586ce8441ec2c67b454f5d.tar.gz lwn-f3221361dc85d4de22586ce8441ec2c67b454f5d.zip | |
net: tls: avoid hanging tasks on the tx_lock
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@syzkaller.appspotmail.com
Fixes: 79ffe6087e91 ("net/tls: add a TX lock")
Link: https://lore.kernel.org/all/000000000000e412e905f5b46201@google.com/
Cc: stable@vger.kernel.org # wait 4 weeks
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230301002857.2101894-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/tls/tls_sw.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 021d760f9133..635b8bf6b937 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -956,7 +956,9 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) 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)) { @@ -1290,7 +1292,9 @@ int tls_sw_sendpage(struct sock *sk, struct page *page, 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); @@ -2435,11 +2439,19 @@ static void tx_work_handler(struct work_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)); + } } static bool tls_is_tx_ready(struct tls_sw_context_tx *ctx) |