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strparser: Fix incorrect strp->need_bytes value.

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[ Upstream commit 9d0c75bf6e03d9bf80c55b0f677dc9b982958fd5 ]

strp_data_ready resets strp->need_bytes to 0 if strp_peek_len indicates
that the remainder of the message has been received. However,
do_strp_work does not reset strp->need_bytes to 0. If do_strp_work
completes a partial message, the value of strp->need_bytes will continue
to reflect the needed bytes of the previous message, causing
future invocations of strp_data_ready to return early if
strp->need_bytes is less than strp_peek_len. Resetting strp->need_bytes
to 0 in __strp_recv on handing a full message to the upper layer solves
this problem.

__strp_recv also calculates strp->need_bytes using stm->accum_len before
stm->accum_len has been incremented by cand_len. This can cause
strp->need_bytes to be equal to the full length of the message instead
of the full length minus the accumulated length. This, in turn, causes
strp_data_ready to return early, even when there is sufficient data to
complete the partial message. Incrementing stm->accum_len before using
it to calculate strp->need_bytes solves this problem.

Found while testing net/tls_sw recv path.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Doron Roberts-Kedes 2018-04-11 15:05:16 -07:00 • committed by Greg Kroah-Hartman
commit 2f7be12628
1 changed files with 3 additions and 4 deletions
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7
net/strparser/strparser.c
View file

@ -285,9 +285,9 @@ static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
strp_start_rx_timer(strp);
}
rxm->accum_len += cand_len;
strp->rx_need_bytes = rxm->strp.full_len -
rxm->accum_len;
rxm->accum_len += cand_len;
rxm->early_eaten = cand_len;
STRP_STATS_ADD(strp->stats.rx_bytes, cand_len);
desc->count = 0; /* Stop reading socket */
@ -310,6 +310,7 @@ static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
/* Hurray, we have a new message! */
del_timer(&strp->rx_msg_timer);
strp->rx_skb_head = NULL;
strp->rx_need_bytes = 0;
STRP_STATS_INCR(strp->stats.rx_msgs);
/* Give skb to upper layer */
@ -374,9 +375,7 @@ void strp_data_ready(struct strparser *strp)
return;
if (strp->rx_need_bytes) {
if (strp_peek_len(strp) >= strp->rx_need_bytes)
strp->rx_need_bytes = 0;
else
if (strp_peek_len(strp) < strp->rx_need_bytes)
return;
}