From 38f88c45404293bbc027b956def6c10cbd45c616 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 4 Feb 2020 19:26:05 -0800 Subject: bonding/alb: properly access headers in bond_alb_xmit() syzbot managed to send an IPX packet through bond_alb_xmit() and af_packet and triggered a use-after-free. First, bond_alb_xmit() was using ipx_hdr() helper to reach the IPX header, but ipx_hdr() was using the transport offset instead of the network offset. In the particular syzbot report transport offset was 0xFFFF This patch removes ipx_hdr() since it was only (mis)used from bonding. Then we need to make sure IPv4/IPv6/IPX headers are pulled in skb->head before dereferencing anything. BUG: KASAN: use-after-free in bond_alb_xmit+0x153a/0x1590 drivers/net/bonding/bond_alb.c:1452 Read of size 2 at addr ffff8801ce56dfff by task syz-executor.2/18108 (if (ipx_hdr(skb)->ipx_checksum != IPX_NO_CHECKSUM) ...) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: [] __dump_stack lib/dump_stack.c:17 [inline] [] dump_stack+0x14d/0x20b lib/dump_stack.c:53 [] print_address_description+0x6f/0x20b mm/kasan/report.c:282 [] kasan_report_error mm/kasan/report.c:380 [inline] [] kasan_report mm/kasan/report.c:438 [inline] [] kasan_report.cold+0x8c/0x2a0 mm/kasan/report.c:422 [] __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:469 [] bond_alb_xmit+0x153a/0x1590 drivers/net/bonding/bond_alb.c:1452 [] __bond_start_xmit drivers/net/bonding/bond_main.c:4199 [inline] [] bond_start_xmit+0x4f4/0x1570 drivers/net/bonding/bond_main.c:4224 [] __netdev_start_xmit include/linux/netdevice.h:4525 [inline] [] netdev_start_xmit include/linux/netdevice.h:4539 [inline] [] xmit_one net/core/dev.c:3611 [inline] [] dev_hard_start_xmit+0x168/0x910 net/core/dev.c:3627 [] __dev_queue_xmit+0x1f55/0x33b0 net/core/dev.c:4238 [] dev_queue_xmit+0x18/0x20 net/core/dev.c:4278 [] packet_snd net/packet/af_packet.c:3226 [inline] [] packet_sendmsg+0x4919/0x70b0 net/packet/af_packet.c:3252 [] sock_sendmsg_nosec net/socket.c:673 [inline] [] sock_sendmsg+0x12c/0x160 net/socket.c:684 [] __sys_sendto+0x262/0x380 net/socket.c:1996 [] SYSC_sendto net/socket.c:2008 [inline] [] SyS_sendto+0x40/0x60 net/socket.c:2004 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: Jay Vosburgh Cc: Veaceslav Falico Cc: Andy Gospodarek Signed-off-by: David S. Miller --- include/net/ipx.h | 5 ----- 1 file changed, 5 deletions(-) (limited to 'include/net') diff --git a/include/net/ipx.h b/include/net/ipx.h index baf090390998..9d1342807b59 100644 --- a/include/net/ipx.h +++ b/include/net/ipx.h @@ -47,11 +47,6 @@ struct ipxhdr { /* From af_ipx.c */ extern int sysctl_ipx_pprop_broadcasting; -static __inline__ struct ipxhdr *ipx_hdr(struct sk_buff *skb) -{ - return (struct ipxhdr *)skb_transport_header(skb); -} - struct ipx_interface { /* IPX address */ __be32 if_netnum; -- cgit v1.2.3-59-g8ed1b