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sctp: frag_point sanity check

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If for some reason an association's fragmentation point is zero,
sctp_datamsg_from_user will try to endlessly try to divide a message
into zero-sized chunks. This eventually causes kernel panic due to
running out of memory.

Although this situation is quite unlikely, it has occurred before as
reported. I propose to add this simple last-ditch sanity check due to
the severity of the potential consequences.

Signed-off-by: Jakub Audykowicz <jakub.audykowicz@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Audykowicz
2018-12-04 20:27:41 +01:00
committed by David S. Miller
parent b2b7af8611
commit afd0a8006e
3 changed files with 12 additions and 2 deletions
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3
net/sctp/socket.c
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@@ -3324,8 +3324,7 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned
__u16 datasize = asoc ? sctp_datachk_len(&asoc->stream) :
sizeof(struct sctp_data_chunk);
min_len = sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT,
datasize);
min_len = sctp_min_frag_point(sp, datasize);
max_len = SCTP_MAX_CHUNK_LEN - datasize;
if (val < min_len || val > max_len)