syzbot has found a reproducer for the following crash on:
HEAD commit: 56b697c6 Add linux-next specific files for 20190604
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=122c965aa00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4248d6bc70076f7d
dashboard link: https://syzkaller.appspot.com/bug?extid=9343b7623bc03dc680c1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=102ab292a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f0e27ca00000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+9343b7623bc03dc680c1@xxxxxxxxxxxxxxxxxxxxxxxxx
==================================================================
BUG: KASAN: slab-out-of-bounds in css_task_iter_advance+0x49b/0x540
kernel/cgroup/cgroup.c:4507
Read of size 4 at addr ffff8880a2013d64 by task syz-executor561/8892
CPU: 0 PID: 8892 Comm: syz-executor561 Not tainted 5.2.0-rc3-next-20190604
#8
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
__kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
css_task_iter_advance+0x49b/0x540 kernel/cgroup/cgroup.c:4507
css_task_iter_next+0x101/0x190 kernel/cgroup/cgroup.c:4569
pidlist_array_load+0x1bf/0xa80 kernel/cgroup/cgroup-v1.c:373
cgroup_pidlist_start+0x37e/0x4c0 kernel/cgroup/cgroup-v1.c:442
cgroup_seqfile_start+0xa4/0xd0 kernel/cgroup/cgroup.c:3752
kernfs_seq_start+0xdc/0x190 fs/kernfs/file.c:118
seq_read+0x2a7/0x1110 fs/seq_file.c:224
kernfs_fop_read+0xed/0x560 fs/kernfs/file.c:252
do_loop_readv_writev fs/read_write.c:714 [inline]
do_loop_readv_writev fs/read_write.c:701 [inline]
do_iter_read+0x4a4/0x660 fs/read_write.c:935
vfs_readv+0xf0/0x160 fs/read_write.c:997
do_preadv+0x1c4/0x280 fs/read_write.c:1089
__do_sys_preadv fs/read_write.c:1139 [inline]
__se_sys_preadv fs/read_write.c:1134 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1134
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4471c9
Code: e8 4c bb 02 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 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7fb370bdb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000006dcc58 RCX: 00000000004471c9
RDX: 0000000000000001 RSI: 0000000020000100 RDI: 0000000000000004
RBP: 00000000006dcc50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc5c
R13: 00007fffdb647a6f R14: 00007f7fb370c9c0 R15: 0000000000000001
Allocated by task 8773:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
__do_kmalloc mm/slab.c:3654 [inline]
__kmalloc+0x15c/0x740 mm/slab.c:3663
kmalloc include/linux/slab.h:552 [inline]
tomoyo_realpath_from_path+0xcd/0x7a0 security/tomoyo/realpath.c:277
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_number_perm+0x1dd/0x520 security/tomoyo/file.c:723
tomoyo_file_ioctl+0x23/0x30 security/tomoyo/tomoyo.c:335
security_file_ioctl+0x77/0xc0 security/security.c:1366
ksys_ioctl+0x57/0xd0 fs/ioctl.c:711
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 8773:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3426 [inline]
kfree+0x106/0x2a0 mm/slab.c:3753
tomoyo_realpath_from_path+0x1de/0x7a0 security/tomoyo/realpath.c:319
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_number_perm+0x1dd/0x520 security/tomoyo/file.c:723
tomoyo_file_ioctl+0x23/0x30 security/tomoyo/tomoyo.c:335
security_file_ioctl+0x77/0xc0 security/security.c:1366
ksys_ioctl+0x57/0xd0 fs/ioctl.c:711
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff8880a20127c0
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1444 bytes to the right of
4096-byte region [ffff8880a20127c0, ffff8880a20137c0)
The buggy address belongs to the page:
page:ffffea0002880480 refcount:1 mapcount:0 mapping:ffff8880aa400dc0
index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002311108 ffffea0002885488 ffff8880aa400dc0
raw: 0000000000000000 ffff8880a20127c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8880a2013c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880a2013c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880a2013d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8880a2013d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880a2013e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
