[PATCH 5.11 049/122] net/rds: Avoid potential use after free in rds_send_remove_from_sock

Greg Kroah-Hartman
2021-04-19T13:10:42Z

From: Aditya Pakki <pakki001@umn.edu>

[ Upstream commit 0c85a7e87465f2d4cbc768e245f4f45b2f299b05 ]

In case of rs failure in rds_send_remove_from_sock(), the 'rm' resource
is freed and later under spinlock, causing potential use-after-free.
Set the free pointer to NULL to avoid undefined behavior.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/rds/message.c | 1 +
net/rds/send.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/rds/message.c b/net/rds/message.c
index 799034e0f513..4fc66ff0f1ec 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -180,6 +180,7 @@ void rds_message_put(struct rds_message *rm)
rds_message_purge(rm);

kfree(rm);
+ rm = NULL;
}
}
EXPORT_SYMBOL_GPL(rds_message_put);
diff --git a/net/rds/send.c b/net/rds/send.c
index 985d0b7713ac..fe5264b9d4b3 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -665,7 +665,7 @@ static void rds_send_remove_from_sock(struct list_head *messages, int status)
unlock_and_drop:
spin_unlock_irqrestore(&rm->m_rs_lock, flags);
rds_message_put(rm);
- if (was_on_sock)
+ if (was_on_sock && rm)
rds_message_put(rm);
}

--
2.30.2