[PATCH net 2/2] ax25: fix potential reference counting leak in ax25_addr_ax25dev

From: Duoming Zhou
Date: Thu May 02 2024 - 10:49:47 EST


The reference counting of ax25_dev potentially increase more
than once in ax25_addr_ax25dev(), which will cause memory leak.

In order to fix the above issue, only increase the reference
counting of ax25_dev once, when the res is not null.

Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
---
net/ax25/ax25_dev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index 07723095c60..945af92a7b6 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -37,8 +37,9 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
- ax25_dev_hold(ax25_dev);
}
+ if (res)
+ ax25_dev_hold(ax25_dev);
spin_unlock_bh(&ax25_dev_lock);

return res;
--
2.17.1