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| author | Jakub Audykowicz <jakub.audykowicz@gmail.com> | 2018-12-04 20:27:41 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-12-05 20:37:52 -0800 |
| commit | afd0a8006e98b1890908f81746c94ca5dae29d7c (patch) | |
| tree | 22a7070a7d5b13891bc65368b42bcb18cc56d6f1 | |
| parent | b2b7af861122a0c0f6260155c29a1b2e594cd5b5 (diff) | |
| download | linux-afd0a8006e98b1890908f81746c94ca5dae29d7c.tar.gz | |
sctp: frag_point sanity check
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>
| -rw-r--r-- | include/net/sctp/sctp.h | 5 | ||||
| -rw-r--r-- | net/sctp/chunk.c | 6 | ||||
| -rw-r--r-- | net/sctp/socket.c | 3 |
3 files changed, 12 insertions, 2 deletions
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index ab9242e51d9e0..2abbc15824af9 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -620,4 +620,9 @@ static inline bool sctp_transport_pmtu_check(struct sctp_transport *t) return false; } +static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize) +{ + return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize); +} + #endif /* __net_sctp_h__ */ diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c index ce8087846f059..d2048de86e7c2 100644 --- a/net/sctp/chunk.c +++ b/net/sctp/chunk.c @@ -191,6 +191,12 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, * the packet */ max_data = asoc->frag_point; + if (unlikely(!max_data)) { + max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk), + sctp_datachk_len(&asoc->stream)); + pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%Zu)", + __func__, asoc, max_data); + } /* If the the peer requested that we authenticate DATA chunks * we need to account for bundling of the AUTH chunks along with diff --git a/net/sctp/socket.c b/net/sctp/socket.c index bf618d1b41fd2..b8cebd5a87e5c 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -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) |