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Subject[PATCH 3.16.y-ckt 004/126] RDS-TCP: Recover correctly from pskb_pull()/pksb_trim() failure in rds_tcp_data_recv
Date
3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sowmini Varadhan <sowmini.varadhan@oracle.com>

commit 8ce675ff39b9958d1c10f86cf58e357efaafc856 upstream.

Either of pskb_pull() or pskb_trim() may fail under low memory conditions.
If rds_tcp_data_recv() ignores such failures, the application will
receive corrupted data because the skb has not been correctly
carved to the RDS datagram size.

Avoid this by handling pskb_pull/pskb_trim failure in the same
manner as the skb_clone failure: bail out of rds_tcp_data_recv(), and
retry via the deferred call to rds_send_worker() that gets set up on
ENOMEM from rds_tcp_read_sock()

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
net/rds/tcp_recv.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
index 9ae6e0a264ec..2dd88db4a1a2 100644
--- a/net/rds/tcp_recv.c
+++ b/net/rds/tcp_recv.c
@@ -234,8 +234,15 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
}

to_copy = min(tc->t_tinc_data_rem, left);
- pskb_pull(clone, offset);
- pskb_trim(clone, to_copy);
+ if (!pskb_pull(clone, offset) ||
+ pskb_trim(clone, to_copy)) {
+ pr_warn("rds_tcp_data_recv: pull/trim failed "
+ "left %zu data_rem %zu skb_len %d\n",
+ left, tc->t_tinc_data_rem, skb->len);
+ kfree_skb(clone);
+ desc->error = -ENOMEM;
+ goto out;
+ }
skb_queue_tail(&tinc->ti_skb_list, clone);

rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "

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