Re: [PATCH net v2] sctp: fix a potential buffer overflow in sctp_sched_set_sched()
From: Kuniyuki Iwashima <hidden>
Date: 2023-05-02 17:06:13
Also in:
linux-sctp, lkml
From: Gavrilov Ilia <redacted> Date: Tue, 2 May 2023 13:03:24 +0000
The 'sched' index value must be checked before accessing an element of the 'sctp_sched_ops' array. Otherwise, it can lead to buffer overflow.
OOB access ? But it's not true because it does not happen in the first place.
quoted hunk ↗ jump to hunk
Note that it's harmless since the 'sched' parameter is checked before calling 'sctp_sched_set_sched'. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Reviewed-by: Simon Horman <redacted> Signed-off-by: Ilia.Gavrilov <redacted> --- V2: - Change the order of local variables - Specify the target tree in the subject net/sctp/stream_sched.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)diff --git a/net/sctp/stream_sched.c b/net/sctp/stream_sched.c index 330067002deb..4d076a9b8592 100644 --- a/net/sctp/stream_sched.c +++ b/net/sctp/stream_sched.c@@ -146,18 +146,19 @@ static void sctp_sched_free_sched(struct sctp_stream *stream) int sctp_sched_set_sched(struct sctp_association *asoc, enum sctp_sched_type sched) { - struct sctp_sched_ops *n = sctp_sched_ops[sched]; struct sctp_sched_ops *old = asoc->outqueue.sched; struct sctp_datamsg *msg = NULL; + struct sctp_sched_ops *n; struct sctp_chunk *ch; int i, ret = 0; - if (old == n) - return ret; - if (sched > SCTP_SS_MAX) return -EINVAL;
I'd just remove this check instead because the same test is done in the caller side, sctp_setsockopt_scheduler(), and this errno is never returned. This unnecessary test confuses a reader like sched could be over SCTP_SS_MAX here. Since the OOB access does not happen, I think this patch should go to net-next without the Fixes tag after the merge window. Thanks, Kuniyuki
+ n = sctp_sched_ops[sched]; + if (old == n) + return ret; + if (old) sctp_sched_free_sched(&asoc->stream); -- 2.30.2