commit 4cfae7b23889fd7e6af2e371c3d2f5eb7e49de0b
author Lv Yunlong <lyl2019@mail.ustc.edu.cn> Tue Mar 30 18:59:59 2021 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> Wed Apr 14 08:42:09 2021 +0200
tree 49f004661604e777140214f619c384281ca69f76
parent 05bbe9d85a4c2cbf79aea1023fa8ee8330bfe547

net/rds: Fix a use after free in rds_message_map_pages

[ Upstream commit bdc2ab5c61a5c07388f4820ff21e787b4dfd1ced ]

In rds_message_map_pages, the rm is freed by rds_message_put(rm).
But rm is still used by rm->data.op_sg in return value.

My patch assigns ERR_CAST(rm->data.op_sg) to err before the rm is
freed to avoid the uaf.

Fixes: 7dba92037baf3 ("net/rds: Use ERR_PTR for rds_message_alloc_sgs()")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>