syzbot


KASAN: slab-out-of-bounds Read in macvlan_broadcast

Status: fixed on 2020/02/18 14:31
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 96cc4b69581d macvlan: do not assume mac_header is set in macvlan_broadcast()
First crash: 901d, last: 898d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: KASAN: slab-out-of-bounds Read in macvlan_broadcast (log)
Repro: C syz .config
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: slab-out-of-bounds Read in macvlan_broadcast C done 10 896d 901d 1/1 fixed on 2020/02/10 15:38
linux-4.14 KASAN: slab-out-of-bounds Read in macvlan_broadcast C done 6 896d 901d 1/1 fixed on 2020/02/10 15:38

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in __get_unaligned_cpu32 include/linux/unaligned/packed_struct.h:19 [inline]
BUG: KASAN: slab-out-of-bounds in mc_hash drivers/net/macvlan.c:251 [inline]
BUG: KASAN: slab-out-of-bounds in macvlan_broadcast+0x547/0x620 drivers/net/macvlan.c:277
Read of size 4 at addr ffff8880964b5801 by task syz-executor420/10438

CPU: 0 PID: 10438 Comm: syz-executor420 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:639
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:145
 __get_unaligned_cpu32 include/linux/unaligned/packed_struct.h:19 [inline]
 mc_hash drivers/net/macvlan.c:251 [inline]
 macvlan_broadcast+0x547/0x620 drivers/net/macvlan.c:277
 macvlan_queue_xmit drivers/net/macvlan.c:520 [inline]
 macvlan_start_xmit+0x402/0x77f drivers/net/macvlan.c:559
 __netdev_start_xmit include/linux/netdevice.h:4447 [inline]
 netdev_start_xmit include/linux/netdevice.h:4461 [inline]
 dev_direct_xmit+0x419/0x630 net/core/dev.c:4079
 packet_direct_xmit+0x1a9/0x250 net/packet/af_packet.c:240
 packet_snd net/packet/af_packet.c:2966 [inline]
 packet_sendmsg+0x260d/0x6220 net/packet/af_packet.c:2991
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:659
 __sys_sendto+0x262/0x380 net/socket.c:1985
 __do_sys_sendto net/socket.c:1997 [inline]
 __se_sys_sendto net/socket.c:1993 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1993
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442b99
Code: e8 8c 07 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd02f17ed8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000442b99
RDX: 000000000000000e RSI: 0000000020000080 RDI: 0000000000000003
RBP: 0000000000016f85 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000403af0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 10310:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3665
 kmalloc include/linux/slab.h:561 [inline]
 tomoyo_realpath_from_path+0xc5/0x660 security/tomoyo/realpath.c:252
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x230/0x430 security/tomoyo/file.c:822
 tomoyo_inode_getattr+0x1d/0x30 security/tomoyo/tomoyo.c:129
 security_inode_getattr+0xf2/0x150 security/security.c:1222
 vfs_getattr+0x25/0x70 fs/stat.c:115
 vfs_statx_fd+0x71/0xc0 fs/stat.c:145
 vfs_fstat include/linux/fs.h:3265 [inline]
 __do_sys_newfstat+0x9b/0x120 fs/stat.c:378
 __se_sys_newfstat fs/stat.c:375 [inline]
 __x64_sys_newfstat+0x54/0x80 fs/stat.c:375
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10310:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:335 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 tomoyo_realpath_from_path+0x1a7/0x660 security/tomoyo/realpath.c:289
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x230/0x430 security/tomoyo/file.c:822
 tomoyo_inode_getattr+0x1d/0x30 security/tomoyo/tomoyo.c:129
 security_inode_getattr+0xf2/0x150 security/security.c:1222
 vfs_getattr+0x25/0x70 fs/stat.c:115
 vfs_statx_fd+0x71/0xc0 fs/stat.c:145
 vfs_fstat include/linux/fs.h:3265 [inline]
 __do_sys_newfstat+0x9b/0x120 fs/stat.c:378
 __se_sys_newfstat fs/stat.c:375 [inline]
 __x64_sys_newfstat+0x54/0x80 fs/stat.c:375
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880964b4000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2049 bytes to the right of
 4096-byte region [ffff8880964b4000, ffff8880964b5000)
The buggy address belongs to the page:
page:ffffea0002592d00 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0
raw: 00fffe0000010200 ffffea0002515388 ffffea000263b608 ffff8880aa402000
raw: 0000000000000000 ffff8880964b4000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880964b5700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880964b5780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880964b5800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8880964b5880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880964b5900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (10):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2020/01/08 05:12 upstream ae6088216ce4 6738e0b3 .config log report syz C
ci-upstream-kasan-gce-selinux-root 2020/01/07 23:14 upstream ae6088216ce4 1bcd407e .config log report syz C
ci-upstream-kasan-gce-root 2020/01/07 07:03 upstream ec7b3f5372e2 53430d97 .config log report syz C
ci-upstream-kasan-gce 2020/01/07 04:22 upstream ec7b3f5372e2 53430d97 .config log report syz C
ci-upstream-net-this-kasan-gce 2020/01/06 17:53 net d89091a4930e 438e1227 .config log report syz C
ci-upstream-net-this-kasan-gce 2020/01/06 14:23 net f11421ba4af7 438e1227 .config log report syz C
ci-upstream-net-kasan-gce 2020/01/06 18:18 net-next de1b23b9b4c1 438e1227 .config log report syz C
ci-upstream-kasan-gce 2020/01/07 07:39 upstream ec7b3f5372e2 53430d97 .config log report syz
ci-upstream-kasan-gce-386 2020/01/07 00:52 upstream c79f46a28239 53430d97 .config log report syz
ci-upstream-net-kasan-gce 2020/01/09 05:58 net-next 53ebeca24a87 ddc3e859 .config log report