From c178e8a1993741fc401ee507a5a544f3192256c8 Mon Sep 17 00:00:00 2001 From: Lv Yunlong Date: Tue, 30 Mar 2021 18:59:59 -0700 Subject: [PATCH] net/rds: Fix a use after free in rds_message_map_pages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ 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 Reviewed-by: Håkon Bugge Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/rds/message.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/rds/message.c b/net/rds/message.c index 2d43e13d6dd5..92b6b22884d4 100644 --- a/net/rds/message.c +++ b/net/rds/message.c @@ -347,8 +347,9 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in rm->data.op_nents = DIV_ROUND_UP(total_len, PAGE_SIZE); rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs); if (IS_ERR(rm->data.op_sg)) { + void *err = ERR_CAST(rm->data.op_sg); rds_message_put(rm); - return ERR_CAST(rm->data.op_sg); + return err; } for (i = 0; i < rm->data.op_nents; ++i) {