2021-03-11 08:47:53

by Lv Yunlong

Subject: [PATCH] net/rds: Fix a use after free in rds_message_map_pages

In rds_message_map_pages, rds_message_put() will free rm.
Maybe store the value of rm->data.op_sg ahead of rds_message_put()
is better. Otherwise other threads could allocate the freed chunk
and may change the value of rm->data.op_sg.

Signed-off-by: Lv Yunlong <[email protected]>
---
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 071a261fdaab..392e3a2f41a0 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)) {
+ struct scatterlist *tmp = rm->data.op_sg;
rds_message_put(rm);
- return ERR_CAST(rm->data.op_sg);
+ return ERR_CAST(tmp);
}

for (i = 0; i < rm->data.op_nents; ++i) {
--
2.25.1

2021-03-19 02:27:12

by Lv Yunlong

Subject: Re: [PATCH] net/rds: Fix a use after free in rds_message_map_pages

Just as a reminder,
there has been no reply to this message for more than a week.

Could someone help to fix this issue?

> -----原始邮件-----
> 发件人: "Lv Yunlong" <[email protected]>
> 发送时间: 2021-03-11 16:46:16 (星期四)
> 收件人: [email protected], [email protected], [email protected]
> 抄送: [email protected], [email protected], [email protected], [email protected], "Lv Yunlong" <[email protected]>
> 主题: [PATCH] net/rds: Fix a use after free in rds_message_map_pages
>
> In rds_message_map_pages, rds_message_put() will free rm.
> Maybe store the value of rm->data.op_sg ahead of rds_message_put()
> is better. Otherwise other threads could allocate the freed chunk
> and may change the value of rm->data.op_sg.
>
> Signed-off-by: Lv Yunlong <[email protected]>
> ---
> 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 071a261fdaab..392e3a2f41a0 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)) {
> + struct scatterlist *tmp = rm->data.op_sg;
> rds_message_put(rm);
> - return ERR_CAST(rm->data.op_sg);
> + return ERR_CAST(tmp);
> }
>
> for (i = 0; i < rm->data.op_nents; ++i) {
> --
> 2.25.1
>