[PATCH net v1] net/rds: reset op_nents when zerocopy page pin fails

[PATCH net v1] net/rds: reset op_nents when zerocopy page pin fails

[Allison Henderson]

When iov_iter_get_pages2() fails in rds_message_zcopy_from_user(),
the pinned pages are released with put_page(), and
rm->data.op_mmp_znotifier is cleared.  But we fail to properly
clear rm->data.op_nents.

Later when rds_message_purge() is called from rds_sendmsg() the
cleanup loop iterates over the incorrectly non zero number of
op_nents and frees them again.

Fix this by properly resetting op_nents when it should be in
rds_message_zcopy_from_user().

Fixes: 0cebaccef3ac ("rds: zerocopy Tx support.")
Signed-off-by: Allison Henderson <achender@kernel.org>
---
 net/rds/message.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/rds/message.c b/net/rds/message.c
index 25fedcb3cd00..7feb0eb6537d 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -448,6 +448,7 @@ static int rds_message_zcopy_from_user(struct rds_message *rm, struct iov_iter *
 
 			for (i = 0; i < rm->data.op_nents; i++)
 				put_page(sg_page(&rm->data.op_sg[i]));
+			rm->data.op_nents = 0;
 			mmp = &rm->data.op_mmp_znotifier->z_mmp;
 			mm_unaccount_pinned_pages(mmp);
 			ret = -EFAULT;
-- 
2.43.0

Re: [PATCH net v1] net/rds: reset op_nents when zerocopy page pin fails

[Simon Horman]

On Tue, May 05, 2026 at 04:43:36PM -0700, Allison Henderson wrote:
> When iov_iter_get_pages2() fails in rds_message_zcopy_from_user(),
> the pinned pages are released with put_page(), and
> rm->data.op_mmp_znotifier is cleared.  But we fail to properly
> clear rm->data.op_nents.
> 
> Later when rds_message_purge() is called from rds_sendmsg() the
> cleanup loop iterates over the incorrectly non zero number of
> op_nents and frees them again.
> 
> Fix this by properly resetting op_nents when it should be in
> rds_message_zcopy_from_user().
> 
> Fixes: 0cebaccef3ac ("rds: zerocopy Tx support.")
> Signed-off-by: Allison Henderson <achender@kernel.org>

Reviewed-by: Simon Horman <horms@kernel.org>