@@ -1403,8 +1403,8 @@ static void sctp_chunk_destroy(struct sctp_chunk *chunk)
BUG_ON(!list_empty(&chunk->list));
list_del_init(&chunk->transmitted_list);
- /* Free the chunk skb data and the SCTP_chunk stub itself. */
- dev_kfree_skb(chunk->skb);
+ consume_skb(chunk->skb);
+ consume_skb(chunk->auth_chunk);
SCTP_DBG_OBJCNT_DEC(chunk);
kmem_cache_free(sctp_chunk_cachep, chunk);
@@ -767,7 +767,6 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net,
/* Make sure that we and the peer are AUTH capable */
if (!net->sctp.auth_enable || !new_asoc->peer.auth_capable) {
- kfree_skb(chunk->auth_chunk);
sctp_association_free(new_asoc);
return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
}
@@ -782,10 +781,6 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net,
auth.transport = chunk->transport;
ret = sctp_sf_authenticate(net, ep, new_asoc, type, &auth);
-
- /* We can now safely free the auth_chunk clone */
- kfree_skb(chunk->auth_chunk);
-
if (ret != SCTP_IERROR_NO_ERROR) {
sctp_association_free(new_asoc);
return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
This is a note to let you know that I have just added a patch titled net: sctp: fix skb leakage in COOKIE ECHO path of chunk->auth_chunk to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.22. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From cbba03ae1a92138809427c3879f7ef41e2c9ec4b Mon Sep 17 00:00:00 2001 From: Daniel Borkmann <dborkman@redhat.com> Date: Tue, 4 Mar 2014 16:35:51 +0100 Subject: net: sctp: fix skb leakage in COOKIE ECHO path of chunk->auth_chunk [ Upstream commit c485658bae87faccd7aed540fd2ca3ab37992310 ] While working on ec0223ec48a9 ("net: sctp: fix sctp_sf_do_5_1D_ce to verify if we/peer is AUTH capable"), we noticed that there's a skb memory leakage in the error path. Running the same reproducer as in ec0223ec48a9 and by unconditionally jumping to the error label (to simulate an error condition) in sctp_sf_do_5_1D_ce() receive path lets kmemleak detector bark about the unfreed chunk->auth_chunk skb clone: Unreferenced object 0xffff8800b8f3a000 (size 256): comm "softirq", pid 0, jiffies 4294769856 (age 110.757s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 89 ab 75 5e d4 01 58 13 00 00 00 00 00 00 00 00 ..u^..X......... backtrace: [<ffffffff816660be>] kmemleak_alloc+0x4e/0xb0 [<ffffffff8119f328>] kmem_cache_alloc+0xc8/0x210 [<ffffffff81566929>] skb_clone+0x49/0xb0 [<ffffffffa0467459>] sctp_endpoint_bh_rcv+0x1d9/0x230 [sctp] [<ffffffffa046fdbc>] sctp_inq_push+0x4c/0x70 [sctp] [<ffffffffa047e8de>] sctp_rcv+0x82e/0x9a0 [sctp] [<ffffffff815abd38>] ip_local_deliver_finish+0xa8/0x210 [<ffffffff815a64af>] nf_reinject+0xbf/0x180 [<ffffffffa04b4762>] nfqnl_recv_verdict+0x1d2/0x2b0 [nfnetlink_queue] [<ffffffffa04aa40b>] nfnetlink_rcv_msg+0x14b/0x250 [nfnetlink] [<ffffffff815a3269>] netlink_rcv_skb+0xa9/0xc0 [<ffffffffa04aa7cf>] nfnetlink_rcv+0x23f/0x408 [nfnetlink] [<ffffffff815a2bd8>] netlink_unicast+0x168/0x250 [<ffffffff815a2fa1>] netlink_sendmsg+0x2e1/0x3f0 [<ffffffff8155cc6b>] sock_sendmsg+0x8b/0xc0 [<ffffffff8155d449>] ___sys_sendmsg+0x369/0x380 What happens is that commit bbd0d59809f9 clones the skb containing the AUTH chunk in sctp_endpoint_bh_rcv() when having the edge case that an endpoint requires COOKIE-ECHO chunks to be authenticated: ---------- INIT[RANDOM; CHUNKS; HMAC-ALGO] ----------> <------- INIT-ACK[RANDOM; CHUNKS; HMAC-ALGO] --------- ------------------ AUTH; COOKIE-ECHO ----------------> <-------------------- COOKIE-ACK --------------------- When we enter sctp_sf_do_5_1D_ce() and before we actually get to the point where we process (and subsequently free) a non-NULL chunk->auth_chunk, we could hit the "goto nomem_init" path from an error condition and thus leave the cloned skb around w/o freeing it. The fix is to centrally free such clones in sctp_chunk_destroy() handler that is invoked from sctp_chunk_free() after all refs have dropped; and also move both kfree_skb(chunk->auth_chunk) there, so that chunk->auth_chunk is either NULL (since sctp_chunkify() allocs new chunks through kmem_cache_zalloc()) or non-NULL with a valid skb pointer. chunk->skb and chunk->auth_chunk are the only skbs in the sctp_chunk structure that need to be handeled. While at it, we should use consume_skb() for both. It is the same as dev_kfree_skb() but more appropriately named as we are not a device but a protocol. Also, this effectively replaces the kfree_skb() from both invocations into consume_skb(). Functions are the same only that kfree_skb() assumes that the frame was being dropped after a failure (e.g. for tools like drop monitor), usage of consume_skb() seems more appropriate in function sctp_chunk_destroy() though. Fixes: bbd0d59809f9 ("[SCTP]: Implement the receive and verification of AUTH chunk") Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Vlad Yasevich <yasevich@gmail.com> Cc: Neil Horman <nhorman@tuxdriver.com> Acked-by: Vlad Yasevich <vyasevich@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/sctp/sm_make_chunk.c | 4 ++-- net/sctp/sm_statefuns.c | 5 ----- 2 files changed, 2 insertions(+), 7 deletions(-) -- 1.8.3.2