From: Neil Horman nhorman@tuxdriver.com
[ Upstream commit 0a8dd9f67cd0da7dc284f48b032ce00db1a68791 ]
syzbot found the following leak in sctp_process_init BUG: memory leak unreferenced object 0xffff88810ef68400 (size 1024): comm "syz-executor273", pid 7046, jiffies 4294945598 (age 28.770s) hex dump (first 32 bytes): 1d de 28 8d de 0b 1b e3 b5 c2 f9 68 fd 1a 97 25 ..(........h...% 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000a02cebbd>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<00000000a02cebbd>] slab_post_alloc_hook mm/slab.h:439 [inline] [<00000000a02cebbd>] slab_alloc mm/slab.c:3326 [inline] [<00000000a02cebbd>] __do_kmalloc mm/slab.c:3658 [inline] [<00000000a02cebbd>] __kmalloc_track_caller+0x15d/0x2c0 mm/slab.c:3675 [<000000009e6245e6>] kmemdup+0x27/0x60 mm/util.c:119 [<00000000dfdc5d2d>] kmemdup include/linux/string.h:432 [inline] [<00000000dfdc5d2d>] sctp_process_init+0xa7e/0xc20 net/sctp/sm_make_chunk.c:2437 [<00000000b58b62f8>] sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline] [<00000000b58b62f8>] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1384 [inline] [<00000000b58b62f8>] sctp_side_effects net/sctp/sm_sideeffect.c:1194 [inline] [<00000000b58b62f8>] sctp_do_sm+0xbdc/0x1d60 net/sctp/sm_sideeffect.c:1165 [<0000000044e11f96>] sctp_assoc_bh_rcv+0x13c/0x200 net/sctp/associola.c:1074 [<00000000ec43804d>] sctp_inq_push+0x7f/0xb0 net/sctp/inqueue.c:95 [<00000000726aa954>] sctp_backlog_rcv+0x5e/0x2a0 net/sctp/input.c:354 [<00000000d9e249a8>] sk_backlog_rcv include/net/sock.h:950 [inline] [<00000000d9e249a8>] __release_sock+0xab/0x110 net/core/sock.c:2418 [<00000000acae44fa>] release_sock+0x37/0xd0 net/core/sock.c:2934 [<00000000963cc9ae>] sctp_sendmsg+0x2c0/0x990 net/sctp/socket.c:2122 [<00000000a7fc7565>] inet_sendmsg+0x64/0x120 net/ipv4/af_inet.c:802 [<00000000b732cbd3>] sock_sendmsg_nosec net/socket.c:652 [inline] [<00000000b732cbd3>] sock_sendmsg+0x54/0x70 net/socket.c:671 [<00000000274c57ab>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2292 [<000000008252aedb>] __sys_sendmsg+0x80/0xf0 net/socket.c:2330 [<00000000f7bf23d1>] __do_sys_sendmsg net/socket.c:2339 [inline] [<00000000f7bf23d1>] __se_sys_sendmsg net/socket.c:2337 [inline] [<00000000f7bf23d1>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2337 [<00000000a8b4131f>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:3
The problem was that the peer.cookie value points to an skb allocated area on the first pass through this function, at which point it is overwritten with a heap allocated value, but in certain cases, where a COOKIE_ECHO chunk is included in the packet, a second pass through sctp_process_init is made, where the cookie value is re-allocated, leaking the first allocation.
Fix is to always allocate the cookie value, and free it when we are done using it.
Signed-off-by: Neil Horman nhorman@tuxdriver.com Reported-by: syzbot+f7e9153b037eac9b1df8@syzkaller.appspotmail.com CC: Marcelo Ricardo Leitner marcelo.leitner@gmail.com CC: "David S. Miller" davem@davemloft.net CC: netdev@vger.kernel.org Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/sm_make_chunk.c | 13 +++---------- net/sctp/sm_sideeffect.c | 5 +++++ 2 files changed, 8 insertions(+), 10 deletions(-)
--- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -2329,7 +2329,6 @@ int sctp_process_init(struct sctp_associ union sctp_addr addr; struct sctp_af *af; int src_match = 0; - char *cookie;
/* We must include the address that the INIT packet came from. * This is the only address that matters for an INIT packet. @@ -2433,14 +2432,6 @@ int sctp_process_init(struct sctp_associ /* Peer Rwnd : Current calculated value of the peer's rwnd. */ asoc->peer.rwnd = asoc->peer.i.a_rwnd;
- /* Copy cookie in case we need to resend COOKIE-ECHO. */ - cookie = asoc->peer.cookie; - if (cookie) { - asoc->peer.cookie = kmemdup(cookie, asoc->peer.cookie_len, gfp); - if (!asoc->peer.cookie) - goto clean_up; - } - /* RFC 2960 7.2.1 The initial value of ssthresh MAY be arbitrarily * high (for example, implementations MAY use the size of the receiver * advertised window). @@ -2609,7 +2600,9 @@ do_addr_param: case SCTP_PARAM_STATE_COOKIE: asoc->peer.cookie_len = ntohs(param.p->length) - sizeof(struct sctp_paramhdr); - asoc->peer.cookie = param.cookie->body; + asoc->peer.cookie = kmemdup(param.cookie->body, asoc->peer.cookie_len, gfp); + if (!asoc->peer.cookie) + retval = 0; break;
case SCTP_PARAM_HEARTBEAT_INFO: --- a/net/sctp/sm_sideeffect.c +++ b/net/sctp/sm_sideeffect.c @@ -898,6 +898,11 @@ static void sctp_cmd_new_state(struct sc asoc->rto_initial; }
+ if (sctp_state(asoc, ESTABLISHED)) { + kfree(asoc->peer.cookie); + asoc->peer.cookie = NULL; + } + if (sctp_state(asoc, ESTABLISHED) || sctp_state(asoc, CLOSED) || sctp_state(asoc, SHUTDOWN_RECEIVED)) {