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Subject[PATCH 5.1 02/70] Fix memory leak in sctp_process_init
Date
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)) {

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