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authorEric Dumazet <edumazet@google.com>2021-03-31 02:43:43 +0300
committerDavid S. Miller <davem@davemloft.net>2021-03-31 03:40:46 +0300
commit61431a5907fc36d0738e9a547c7e1556349a03e9 (patch)
tree5a64dbc926bb5988e3b50770fca9d21c51c43912 /include/linux/virtio_net.h
parentc056d480b40a68f2520ccc156c7fae672d69d57d (diff)
downloadlinux-61431a5907fc36d0738e9a547c7e1556349a03e9.tar.xz
net: ensure mac header is set in virtio_net_hdr_to_skb()
Commit 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct") added a call to dev_parse_header_protocol() but mac_header is not yet set. This means that eth_hdr() reads complete garbage, and syzbot complained about it [1] This patch resets mac_header earlier, to get more coverage about this change. Audit of virtio_net_hdr_to_skb() callers shows that this change should be safe. [1] BUG: KASAN: use-after-free in eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282 Read of size 2 at addr ffff888017a6200b by task syz-executor313/8409 CPU: 1 PID: 8409 Comm: syz-executor313 Not tainted 5.12.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282 dev_parse_header_protocol include/linux/netdevice.h:3177 [inline] virtio_net_hdr_to_skb.constprop.0+0x99d/0xcd0 include/linux/virtio_net.h:83 packet_snd net/packet/af_packet.c:2994 [inline] packet_sendmsg+0x2325/0x52b0 net/packet/af_packet.c:3031 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:674 sock_no_sendpage+0xf3/0x130 net/core/sock.c:2860 kernel_sendpage.part.0+0x1ab/0x350 net/socket.c:3631 kernel_sendpage net/socket.c:3628 [inline] sock_sendpage+0xe5/0x140 net/socket.c:947 pipe_to_sendpage+0x2ad/0x380 fs/splice.c:364 splice_from_pipe_feed fs/splice.c:418 [inline] __splice_from_pipe+0x43e/0x8a0 fs/splice.c:562 splice_from_pipe fs/splice.c:597 [inline] generic_splice_sendpage+0xd4/0x140 fs/splice.c:746 do_splice_from fs/splice.c:767 [inline] do_splice+0xb7e/0x1940 fs/splice.c:1079 __do_splice+0x134/0x250 fs/splice.c:1144 __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice fs/splice.c:1332 [inline] __x64_sys_splice+0x198/0x250 fs/splice.c:1332 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Balazs Nemeth <bnemeth@redhat.com> Cc: Willem de Bruijn <willemb@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/virtio_net.h')
-rw-r--r--include/linux/virtio_net.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 6b5fcfa1e555..98775d7fa696 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -62,6 +62,8 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
return -EINVAL;
}
+ skb_reset_mac_header(skb);
+
if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);