[PATCH AUTOSEL 4.14 22/25] net/rds: Avoid potential use after free in rds_send_remove_from_sock

From: Sasha Levin
Date: Mon Apr 12 2021 - 12:42:26 EST


From: Aditya Pakki <pakki001@xxxxxxx>

[ 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@xxxxxxx>
Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 4318cc9b78f7..b6765ead733b 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -91,6 +91,7 @@ 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 23f2d81e7967..3a8e1f72bf33 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -645,7 +645,7 @@ 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