syzbot


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

Status: fixed on 2020/02/10 15:38
Reported-by: syzbot+575d3bd83510e5dc4102@syzkaller.appspotmail.com
Fix commit: 5f3274c53ae7 macvlan: do not assume mac_header is set in macvlan_broadcast()
First crash: 901d, last: 896d

Fix bisection: fixed by (bisect log) :
commit 5f3274c53ae7049755b29ec0c351f145cb68270c
Author: Eric Dumazet <edumazet@google.com>
Date: Mon Jan 6 20:30:48 2020 +0000

  macvlan: do not assume mac_header is set in macvlan_broadcast()

similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in macvlan_broadcast C done 10 898d 901d 16/22 fixed on 2020/02/18 14:31
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:
IPv6: ADDRCONF(NETDEV_UP): macvlan0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): macvlan1: link is not ready
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
==================================================================
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:255 [inline]
BUG: KASAN: slab-out-of-bounds in macvlan_broadcast+0x57c/0x660 drivers/net/macvlan.c:281
Read of size 4 at addr ffff8880a4c86501 by task syz-executor075/8207

CPU: 1 PID: 8207 Comm: syz-executor075 Not tainted 4.19.93-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.cold+0x7c/0x20d mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:443
 __get_unaligned_cpu32 include/linux/unaligned/packed_struct.h:19 [inline]
 mc_hash drivers/net/macvlan.c:255 [inline]
 macvlan_broadcast+0x57c/0x660 drivers/net/macvlan.c:281
 macvlan_queue_xmit drivers/net/macvlan.c:524 [inline]
 macvlan_start_xmit+0x408/0x785 drivers/net/macvlan.c:563
 __netdev_start_xmit include/linux/netdevice.h:4308 [inline]
 netdev_start_xmit include/linux/netdevice.h:4317 [inline]
 dev_direct_xmit+0x34d/0x650 net/core/dev.c:3909
 packet_direct_xmit+0xf9/0x170 net/packet/af_packet.c:246
 packet_snd net/packet/af_packet.c:2958 [inline]
 packet_sendmsg+0x3bb2/0x6440 net/packet/af_packet.c:2983
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:632
 __sys_sendto+0x262/0x380 net/socket.c:1787
 __do_sys_sendto net/socket.c:1799 [inline]
 __se_sys_sendto net/socket.c:1795 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1795
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442529
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 5b 10 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffdba266a58 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000442529
RDX: 000000000000000e RSI: 0000000020000080 RDI: 0000000000000003
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000403aa0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 7297:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x700 mm/slab.c:3559
 getname_flags fs/namei.c:140 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:129
 user_path_at_empty+0x2f/0x50 fs/namei.c:2608
 user_path_at include/linux/namei.h:57 [inline]
 do_faccessat+0x262/0x7f0 fs/open.c:397
 __do_sys_access fs/open.c:449 [inline]
 __se_sys_access fs/open.c:447 [inline]
 __x64_sys_access+0x59/0x80 fs/open.c:447
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7297:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3765
 putname+0xef/0x130 fs/namei.c:261
 filename_lookup+0x28f/0x410 fs/namei.c:2357
 user_path_at_empty+0x43/0x50 fs/namei.c:2608
 user_path_at include/linux/namei.h:57 [inline]
 do_faccessat+0x262/0x7f0 fs/open.c:397
 __do_sys_access fs/open.c:449 [inline]
 __se_sys_access fs/open.c:447 [inline]
 __x64_sys_access+0x59/0x80 fs/open.c:447
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a4c86d00
 which belongs to the cache names_cache of size 4096
The buggy address is located 2047 bytes to the left of
 4096-byte region [ffff8880a4c86d00, ffff8880a4c87d00)
The buggy address belongs to the page:
page:ffffea0002932180 count:1 mapcount:0 mapping:ffff88821bc47980 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea0002a0fc08 ffffea0002921e08 ffff88821bc47980
raw: 0000000000000000 ffff8880a4c86d00 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a4c86400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a4c86480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a4c86500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8880a4c86580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a4c86600: 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
ci2-linux-4-19 2020/01/06 18:33 linux-4.19.y 3d40d7117e35 438e1227 .config log report syz C
ci2-linux-4-19 2020/01/06 15:54 linux-4.19.y 3d40d7117e35 438e1227 .config log report syz C
ci2-linux-4-19 2020/01/06 14:43 linux-4.19.y 3d40d7117e35 438e1227 .config log report syz C
ci2-linux-4-19 2020/01/06 14:20 linux-4.19.y 3d40d7117e35 438e1227 .config log report syz C
ci2-linux-4-19 2020/01/07 04:22 linux-4.19.y 3d40d7117e35 53430d97 .config log report syz
ci2-linux-4-19 2020/01/11 09:10 linux-4.19.y cb1f9a169a0e 4c04afaa .config log report
ci2-linux-4-19 2020/01/10 16:10 linux-4.19.y cb1f9a169a0e 532ec44e .config log report
ci2-linux-4-19 2020/01/10 07:15 linux-4.19.y cb1f9a169a0e 4de4e9f0 .config log report
ci2-linux-4-19 2020/01/09 05:56 linux-4.19.y 3d40d7117e35 ddc3e859 .config log report
ci2-linux-4-19 2020/01/06 13:53 linux-4.19.y 3d40d7117e35 438e1227 .config log report