From: Allison Henderson <allison.henderson@xxxxxxxxxx>
Functions rds_still_queued and rds_clear_recv_queue lock a given socket
in order to safely iterate over the incoming rds messages. However
calling rds_inc_put while under this lock creates a potential deadlock.
rds_inc_put may eventually call rds_message_purge, which will lock
m_rs_lock. This is the incorrect locking order since m_rs_lock is
meant to be locked before the socket. To fix this, we move the message
item to a local list or variable that wont need rs_recv_lock protection.
Then we can safely call rds_inc_put on any item stored locally after
rs_recv_lock is released.
Fixes: bdbe6fbc6a2f ("RDS: recv.c")
Reported-by: syzbot+f9db6ff27b9bfdcfeca0@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+dcd73ff9291e6d34b3ab@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
---
net/rds/recv.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/net/rds/recv.c b/net/rds/recv.c
index c71b923764fd..5627f80013f8 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -425,6 +425,7 @@ static int rds_still_queued(struct rds_sock *rs, struct rds_incoming *inc,
struct sock *sk = rds_rs_to_sk(rs);
int ret = 0;
unsigned long flags;
+ struct rds_incoming *to_drop = NULL;
write_lock_irqsave(&rs->rs_recv_lock, flags);
if (!list_empty(&inc->i_item)) {
@@ -435,11 +436,14 @@ static int rds_still_queued(struct rds_sock *rs, struct rds_incoming *inc,
-be32_to_cpu(inc->i_hdr.h_len),
inc->i_hdr.h_dport);
list_del_init(&inc->i_item);
- rds_inc_put(inc);
+ to_drop = inc;
}
}
write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+ if (to_drop)
+ rds_inc_put(to_drop);
+
rdsdebug("inc %p rs %p still %d dropped %d\n", inc, rs, ret, drop);
return ret;
}
@@ -758,16 +762,21 @@ void rds_clear_recv_queue(struct rds_sock *rs)
struct sock *sk = rds_rs_to_sk(rs);
struct rds_incoming *inc, *tmp;
unsigned long flags;
+ LIST_HEAD(to_drop);
write_lock_irqsave(&rs->rs_recv_lock, flags);
list_for_each_entry_safe(inc, tmp, &rs->rs_recv_queue, i_item) {
rds_recv_rcvbuf_delta(rs, sk, inc->i_conn->c_lcong,
-be32_to_cpu(inc->i_hdr.h_len),
inc->i_hdr.h_dport);
+ list_move(&inc->i_item, &to_drop);
+ }
+ write_unlock_irqrestore(&rs->rs_recv_lock, flags);
+
+ list_for_each_entry_safe(inc, tmp, &to_drop, i_item) {
list_del_init(&inc->i_item);
rds_inc_put(inc);
}
- write_unlock_irqrestore(&rs->rs_recv_lock, flags);
}
/*
--
2.34.1
