sctp: reset owner sk for data chunks on out queues when migrating a sock

Linux Kernel / Linux Kernel - Xin Long [gmail.com] - 29 October 2017 03:06 EDT

Now when migrating sock to another one in sctp_sock_migrate(), it only resets owner sk for the data in receive queues, not the chunks on out queues.

It would cause that data chunks length on the sock is not consistent with sk sk_wmem_alloc. When closing the sock or freeing these chunks, the old sk would never be freed, and the new sock may crash due to the overflow sk_wmem_alloc.

syzbot found this issue with this series:

r0 = socket$inet_sctp() sendto$inet(r0) listen(r0) accept4(r0) close(r0)

Although listen() should have returned error when one TCP-style socket is in connecting (I may fix this one in another patch), it could also be reproduced by peeling off an assoc.

This issue is there since very beginning.

This patch is to reset owner sk for the chunks on out queues so that sk sk_wmem_alloc has correct value after accept one sock or peeloff an assoc to one sock.

Note that when resetting owner sk for chunks on outqueue, it has to sctp_clear_owner_w/skb_orphan chunks before changing assoc->base.sk first and then sctp_set_owner_w them after changing assoc->base.sk, due to that sctp_wfree and it's callees are using assoc->base.sk.

d04adf1b3551 sctp: reset owner sk for data chunks on out queues when migrating a sock
net/sctp/socket.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

Upstream: git.kernel.org


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