From: Eric Dumazet edumazet@google.com
[ Upstream commit 55cd9f67f1e45de8517cdaab985fb8e56c0bc1d8 ]
It is possible for malicious userspace to set TCF_EM_SIMPLE bit even for matches that should not have this bit set.
This can fool two places using tcf_em_is_simple()
1) tcf_em_tree_destroy() -> memory leak of em->data if ops->destroy() is NULL
2) tcf_em_tree_dump() wrongly report/leak 4 low-order bytes of a kernel pointer.
BUG: memory leak unreferenced object 0xffff888121850a40 (size 32): comm "syz-executor927", pid 7193, jiffies 4294941655 (age 19.840s) hex dump (first 32 bytes): 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000f67036ea>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] [<00000000f67036ea>] slab_post_alloc_hook mm/slab.h:586 [inline] [<00000000f67036ea>] slab_alloc mm/slab.c:3320 [inline] [<00000000f67036ea>] __do_kmalloc mm/slab.c:3654 [inline] [<00000000f67036ea>] __kmalloc_track_caller+0x165/0x300 mm/slab.c:3671 [<00000000fab0cc8e>] kmemdup+0x27/0x60 mm/util.c:127 [<00000000d9992e0a>] kmemdup include/linux/string.h:453 [inline] [<00000000d9992e0a>] em_nbyte_change+0x5b/0x90 net/sched/em_nbyte.c:32 [<000000007e04f711>] tcf_em_validate net/sched/ematch.c:241 [inline] [<000000007e04f711>] tcf_em_tree_validate net/sched/ematch.c:359 [inline] [<000000007e04f711>] tcf_em_tree_validate+0x332/0x46f net/sched/ematch.c:300 [<000000007a769204>] basic_set_parms net/sched/cls_basic.c:157 [inline] [<000000007a769204>] basic_change+0x1d7/0x5f0 net/sched/cls_basic.c:219 [<00000000e57a5997>] tc_new_tfilter+0x566/0xf70 net/sched/cls_api.c:2104 [<0000000074b68559>] rtnetlink_rcv_msg+0x3b2/0x4b0 net/core/rtnetlink.c:5415 [<00000000b7fe53fb>] netlink_rcv_skb+0x61/0x170 net/netlink/af_netlink.c:2477 [<00000000e83a40d0>] rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5442 [<00000000d62ba933>] netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] [<00000000d62ba933>] netlink_unicast+0x223/0x310 net/netlink/af_netlink.c:1328 [<0000000088070f72>] netlink_sendmsg+0x2c0/0x570 net/netlink/af_netlink.c:1917 [<00000000f70b15ea>] sock_sendmsg_nosec net/socket.c:639 [inline] [<00000000f70b15ea>] sock_sendmsg+0x54/0x70 net/socket.c:659 [<00000000ef95a9be>] ____sys_sendmsg+0x2d0/0x300 net/socket.c:2330 [<00000000b650f1ab>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2384 [<0000000055bfa74a>] __sys_sendmsg+0x80/0xf0 net/socket.c:2417 [<000000002abac183>] __do_sys_sendmsg net/socket.c:2426 [inline] [<000000002abac183>] __se_sys_sendmsg net/socket.c:2424 [inline] [<000000002abac183>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2424
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot+03c4738ed29d5d366ddf@syzkaller.appspotmail.com Cc: Cong Wang xiyou.wangcong@gmail.com Acked-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/ematch.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/sched/ematch.c +++ b/net/sched/ematch.c @@ -242,6 +242,9 @@ static int tcf_em_validate(struct tcf_pr goto errout;
if (em->ops->change) { + err = -EINVAL; + if (em_hdr->flags & TCF_EM_SIMPLE) + goto errout; err = em->ops->change(net, data, data_len, em); if (err < 0) goto errout;