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Subject[PATCH AUTOSEL for 4.14 019/110] sctp: fix the issue that a __u16 variable may overflow in sctp_ulpq_renege
Date
From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit 5c468674d17056148da06218d4da5d04baf22eac ]

Now when reneging events in sctp_ulpq_renege(), the variable freed
could be increased by a __u16 value twice while freed is of __u16
type. It means freed may overflow at the second addition.

This patch is to fix it by using __u32 type for 'freed', while at
it, also to remove 'if (chunk)' check, as all renege commands are
generated in sctp_eat_data and it can't be NULL.

Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
net/sctp/ulpqueue.c | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c
index a71be33f3afe..e36ec5dd64c6 100644
--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -1084,29 +1084,21 @@ void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
gfp_t gfp)
{
- struct sctp_association *asoc;
- __u16 needed, freed;
-
- asoc = ulpq->asoc;
+ struct sctp_association *asoc = ulpq->asoc;
+ __u32 freed = 0;
+ __u16 needed;

- if (chunk) {
- needed = ntohs(chunk->chunk_hdr->length);
- needed -= sizeof(struct sctp_data_chunk);
- } else
- needed = SCTP_DEFAULT_MAXWINDOW;
-
- freed = 0;
+ needed = ntohs(chunk->chunk_hdr->length) -
+ sizeof(struct sctp_data_chunk);

if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
freed = sctp_ulpq_renege_order(ulpq, needed);
- if (freed < needed) {
+ if (freed < needed)
freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
- }
}
/* If able to free enough room, accept this chunk. */
- if (chunk && (freed >= needed)) {
- int retval;
- retval = sctp_ulpq_tail_data(ulpq, chunk, gfp);
+ if (freed >= needed) {
+ int retval = sctp_ulpq_tail_data(ulpq, chunk, gfp);
/*
* Enter partial delivery if chunk has not been
* delivered; otherwise, drain the reassembly queue.
--
2.11.0
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