On Tue, May 28, 2019 at 05:01:13PM -0700, Christoph Paasch wrote:
> When building the erspan header for either v1 or v2, the eth_hdr()
> does not point to the right inner packet's eth_hdr,
> causing kasan report use-after-free and slab-out-of-bouds read.
>
> The patch fixes the following syzkaller issues:
> [1] BUG: KASAN: slab-out-of-bounds in erspan_xmit+0x22d4/0x2430
> net/ipv4/ip_gre.c:735
> [2] BUG: KASAN: slab-out-of-bounds in erspan_build_header+0x3bf/0x3d0
> net/ipv4/ip_gre.c:698
> [3] BUG: KASAN: use-after-free in erspan_xmit+0x22d4/0x2430
> net/ipv4/ip_gre.c:735
> [4] BUG: KASAN: use-after-free in erspan_build_header+0x3bf/0x3d0
> net/ipv4/ip_gre.c:698
>
> [2] CPU: 0 PID: 3654 Comm: syzkaller377964 Not tainted 4.15.0-rc9+ #185
> 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+0x194/0x257 lib/dump_stack.c:53
> print_address_description+0x73/0x250 mm/kasan/report.c:252
> kasan_report_error mm/kasan/report.c:351 [inline]
> kasan_report+0x25b/0x340 mm/kasan/report.c:409
> __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
> erspan_build_header+0x3bf/0x3d0 net/ipv4/ip_gre.c:698
> erspan_xmit+0x3b8/0x13b0 net/ipv4/ip_gre.c:740
> __netdev_start_xmit include/linux/netdevice.h:4042 [inline]
> netdev_start_xmit include/linux/netdevice.h:4051 [inline]
> packet_direct_xmit+0x315/0x6b0 net/packet/af_packet.c:266
> packet_snd net/packet/af_packet.c:2943 [inline]
> packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2968
> sock_sendmsg_nosec net/socket.c:638 [inline]
> sock_sendmsg+0xca/0x110 net/socket.c:648
> SYSC_sendto+0x361/0x5c0 net/socket.c:1729
> SyS_sendto+0x40/0x50 net/socket.c:1697
> do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
> do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
> entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
> RIP: 0023:0xf7fcfc79
> RSP: 002b:00000000ffc6976c EFLAGS: 00000286 ORIG_RAX: 0000000000000171
> RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020011000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020008000
> RBP: 000000000000001c R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>
> Commit b423d13c08a6 ("net: erspan: fix use-after-free") fixed the
> use-after-free. The root-cause change (commit 84e54fe0a5ea ("gre:
> introduce native tunnel support for ERSPAN")) made it into 4.14.
>
> Thus, the fix needs to be backported to 4.14 as well.
>
> Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
> Cc: William Tu <u9012...@gmail.com>
> Signed-off-by: Christoph Paasch <cpaa...@apple.com>
> ---
>
> Notes:
> This should *only* go into 4.14.
What is the git commit id of this patch in Linus's tree?
thanks,
greg k-h
