syzbot


KASAN: use-after-free Read in string

Status: auto-closed as invalid on 2019/10/23 10:48
Reported-by: syzbot+6029a17962d7404ecd12@syzkaller.appspotmail.com
First crash: 1160d, last: 1160d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in string 2 1159d 1168d 0/1 auto-closed as invalid on 2019/10/24 04:08
upstream KASAN: use-after-free Read in string C 247 1155d 1395d 13/22 fixed on 2019/06/14 18:22

Sample crash report:
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa6ad5d26d4
R13: 00000000004c362f R14: 00000000004d6ad0 R15: 0000000000000005
input: syz1 as /devices/virtual/input/input154
==================================================================
BUG: KASAN: use-after-free in string+0x1b1/0x1d0 lib/vsprintf.c:593
Read of size 1 at addr ffff8880a577f840 by task syz-executor.4/20889

CPU: 1 PID: 20889 Comm: syz-executor.4 Not tainted 4.14.113 #3
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+0x138/0x19c lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xaf/0x2b5 mm/kasan/report.c:393
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
 string+0x1b1/0x1d0 lib/vsprintf.c:593
 vsnprintf+0x75b/0x1570 lib/vsprintf.c:2181
 add_uevent_var+0x126/0x290 lib/kobject_uevent.c:573
 input_dev_uevent+0x159/0x750 drivers/input/input.c:1594
 dev_uevent+0x2f5/0x540 drivers/base/core.c:932
 kobject_uevent_env+0x45e/0xc41 lib/kobject_uevent.c:423
 kobject_uevent+0x20/0x26 lib/kobject_uevent.c:550
 kobject_cleanup lib/kobject.c:633 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put.cold+0x168/0x2ff lib/kobject.c:692
 put_device+0x20/0x30 drivers/base/core.c:1954
 input_put_device include/linux/input.h:349 [inline]
 evdev_free+0x51/0x70 drivers/input/evdev.c:363
 device_release+0x7d/0x1b0 drivers/base/core.c:820
 kobject_cleanup lib/kobject.c:646 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put.cold+0x26f/0x2ff lib/kobject.c:692
 cdev_default_release+0x41/0x50 fs/char_dev.c:607
 kobject_cleanup lib/kobject.c:646 [inline]
 kobject_release lib/kobject.c:675 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put.cold+0x26f/0x2ff lib/kobject.c:692
 cdev_put.part.0+0x39/0x50 fs/char_dev.c:368
 cdev_put+0x20/0x30 fs/char_dev.c:366
 __fput+0x64c/0x7a0 fs/file_table.c:214
 ____fput+0x16/0x20 fs/file_table.c:244
 task_work_run+0x119/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:267 [inline]
 do_syscall_64+0x4a9/0x630 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x412b61
RSP: 002b:00007ffd76fce290 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000412b61
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 000000004c6c24a0 R09: 000000004c6c24a4
R10: 00007ffd76fce370 R11: 0000000000000293 R12: 000000000073c900
R13: 000000000073c900 R14: 0000000000095db0 R15: 000000000073bfac

Allocated by task 20892:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc_track_caller+0x159/0x790 mm/slab.c:3735
 kstrndup+0x50/0xd0 mm/util.c:98
 uinput_dev_setup+0x187/0x2a0 drivers/input/misc/uinput.c:438
 uinput_ioctl_handler.isra.0+0x422/0x18a0 drivers/input/misc/uinput.c:847
 uinput_ioctl+0x4a/0x60 drivers/input/misc/uinput.c:1010
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7b9/0x1070 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 20892:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 uinput_destroy_device+0xeb/0x220 drivers/input/misc/uinput.c:266
 uinput_ioctl_handler.isra.0+0x12f/0x18a0 drivers/input/misc/uinput.c:843
 uinput_ioctl+0x4a/0x60 drivers/input/misc/uinput.c:1010
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7b9/0x1070 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a577f840
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880a577f840, ffff8880a577f860)
The buggy address belongs to the page:
page:ffffea000295dfc0 count:1 mapcount:0 mapping:ffff8880a577f000 index:0xffff8880a577ffc1
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff8880a577f000 ffff8880a577ffc1 000000010000003d
raw: ffffea00024bc360 ffffea00022864e0 ffff8880aa8001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a577f700: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a577f780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a577f800: 00 00 01 fc fc fc fc fc fb fb fb fb fc fc fc fc
                                           ^
 ffff8880a577f880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a577f900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2019/04/26 10:47 linux-4.14.y 68d7a45eec10 b617407b .config log report