On Wed, Feb 14, 2024 at 3:23 AM Dmitry Antipov <dmantipov@xxxxxxxxx> wrote: > > In case of GSO, 'chunk->skb' pointer may point to an entry from > fraglist created in 'sctp_packet_gso_append()'. To avoid freeing > random fraglist entry (and so undefined behavior and/or memory > leak), introduce 'sctp_inq_chunk_free()' helper to ensure that > 'chunk->skb' is set to 'chunk->head_skb' (i.e. fraglist head) > before calling 'sctp_chunk_free()', and use the aforementioned > helper in 'sctp_inq_pop()' as well. > > Reported-by: syzbot+8bb053b5d63595ab47db@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?id=0d8351bbe54fd04a492c2daab0164138db008042 > Fixes: 90017accff61 ("sctp: Add GSO support") > Suggested-by: Xin Long <lucien.xin@xxxxxxxxx> > Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> Acked-by: Xin Long <lucien.xin@xxxxxxxxx> > --- > v3: https://lore.kernel.org/netdev/CADvbK_cjg7kd7uFWxPBpwMAxwsuCki791zQ7D01y+vk0R5wTSQ@xxxxxxxxxxxxxx > - rename helper to 'sctp_inq_chunk_free()' (Xin Long) > v2: https://lore.kernel.org/netdev/20240209134703.63a9167b@xxxxxxxxxx > - factor the fix out to helper function (Jakub Kicinski) > --- > net/sctp/inqueue.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c > index 7182c5a450fb..5c1652181805 100644 > --- a/net/sctp/inqueue.c > +++ b/net/sctp/inqueue.c > @@ -38,6 +38,14 @@ void sctp_inq_init(struct sctp_inq *queue) > INIT_WORK(&queue->immediate, NULL); > } > > +/* Properly release the chunk which is being worked on. */ > +static inline void sctp_inq_chunk_free(struct sctp_chunk *chunk) > +{ > + if (chunk->head_skb) > + chunk->skb = chunk->head_skb; > + sctp_chunk_free(chunk); > +} > + > /* Release the memory associated with an SCTP inqueue. */ > void sctp_inq_free(struct sctp_inq *queue) > { > @@ -53,7 +61,7 @@ void sctp_inq_free(struct sctp_inq *queue) > * free it as well. > */ > if (queue->in_progress) { > - sctp_chunk_free(queue->in_progress); > + sctp_inq_chunk_free(queue->in_progress); > queue->in_progress = NULL; > } > } > @@ -130,9 +138,7 @@ struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue) > goto new_skb; > } > > - if (chunk->head_skb) > - chunk->skb = chunk->head_skb; > - sctp_chunk_free(chunk); > + sctp_inq_chunk_free(chunk); > chunk = queue->in_progress = NULL; > } else { > /* Nothing to do. Next chunk in the packet, please. */ > -- > 2.43.0 >
