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net/rds: Fix a use after free in rds_message_map_pages 

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: 7dba92037b ("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>
This commit is contained in:
Lv Yunlong 2021-03-30 18:59:59 -07:00 committed by David S. Miller
parent d47ec7a0a7
commit bdc2ab5c61
1 changed files with 2 additions and 1 deletions
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3
net/rds/message.c
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@ -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) {