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| author | Dan Carpenter <dan.carpenter@oracle.com> | 2017-09-14 02:00:54 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-14 02:59:47 +0300 |
| commit | fa5f7b51fc3080c2b195fa87c7eca7c05e56f673 (patch) | |
| tree | 1396532cdf8f95a14d447111aad03c60440aef9f | |
| parent | 6fa9c623a03c560178e0dcec23f59dbfd29b21b9 (diff) | |
| download | linux-fa5f7b51fc3080c2b195fa87c7eca7c05e56f673.tar.xz | |
sctp: potential read out of bounds in sctp_ulpevent_type_enabled()
This code causes a static checker warning because Smatch doesn't trust
anything that comes from skb->data. I've reviewed this code and I do
think skb->data can be controlled by the user here.
The sctp_event_subscribe struct has 13 __u8 fields and we want to see
if ours is non-zero. sn_type can be any value in the 0-USHRT_MAX range.
We're subtracting SCTP_SN_TYPE_BASE which is 1 << 15 so we could read
either before the start of the struct or after the end.
This is a very old bug and it's surprising that it would go undetected
for so long but my theory is that it just doesn't have a big impact so
it would be hard to notice.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/sctp/ulpevent.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/net/sctp/ulpevent.h b/include/net/sctp/ulpevent.h index 1060494ac230..b8c86ec1a8f5 100644 --- a/include/net/sctp/ulpevent.h +++ b/include/net/sctp/ulpevent.h @@ -153,8 +153,12 @@ __u16 sctp_ulpevent_get_notification_type(const struct sctp_ulpevent *event); static inline int sctp_ulpevent_type_enabled(__u16 sn_type, struct sctp_event_subscribe *mask) { + int offset = sn_type - SCTP_SN_TYPE_BASE; char *amask = (char *) mask; - return amask[sn_type - SCTP_SN_TYPE_BASE]; + + if (offset >= sizeof(struct sctp_event_subscribe)) + return 0; + return amask[offset]; } /* Given an event subscription, is this event enabled? */ |