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

syzbot
2019-09-11T20:38:11Z

Hello,

syzbot found the following crash on:

HEAD commit: 1e3778cb Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15bdfc5e600000
kernel config: https://syzkaller.appspot.com/x/.config?x=b89bb446a3faaba4
dashboard link: https://syzkaller.appspot.com/bug?extid=46f1dd7dbbe2bfb98b10
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1709421a600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=168fc4b2600000

The bug was bisected to:

commit a87f854ddcf7ff7e044d72db0aa6da82f26d69a6
Author: Neil Armstrong <narmstrong@baylibre.com>
Date: Wed Oct 11 15:39:40 2017 +0000

ARM64: dts: meson-gx: remove unnecessary uart compatible

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17e78a6e600000
final crash: https://syzkaller.appspot.com/x/report.txt?x=14178a6e600000
console output: https://syzkaller.appspot.com/x/log.txt?x=10178a6e600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+46f1dd7dbbe2bfb98b10@syzkaller.appspotmail.com
Fixes: a87f854ddcf7 ("ARM64: dts: meson-gx: remove unnecessary uart
compatible")

L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and
https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for
details.
==================================================================
BUG: KASAN: slab-out-of-bounds in handle_vmptrld
arch/x86/kvm/vmx/nested.c:4789 [inline]
BUG: KASAN: slab-out-of-bounds in handle_vmptrld+0x777/0x800
arch/x86/kvm/vmx/nested.c:4749
Read of size 4 at addr ffff888091e10000 by task syz-executor758/10006

CPU: 1 PID: 10006 Comm: syz-executor758 Not tainted 5.3.0-rc7+ #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+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+0x12/0x17 mm/kasan/common.c:618
__asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:142
handle_vmptrld arch/x86/kvm/vmx/nested.c:4789 [inline]
handle_vmptrld+0x777/0x800 arch/x86/kvm/vmx/nested.c:4749
vmx_handle_exit+0x299/0x15e0 arch/x86/kvm/vmx/vmx.c:5886
vcpu_enter_guest+0x1087/0x5e90 arch/x86/kvm/x86.c:8088
vcpu_run arch/x86/kvm/x86.c:8152 [inline]
kvm_arch_vcpu_ioctl_run+0x464/0x1750 arch/x86/kvm/x86.c:8360
kvm_vcpu_ioctl+0x4dc/0xfd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2765
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__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/0x6a0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447269
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 3b d0 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd58df6ad8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffd58df6ae0 RCX: 0000000000447269
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000020003800 R09: 0000000000400e80
R10: 00007ffd58df4f20 R11: 0000000000000246 R12: 0000000000404730
R13: 00000000004047c0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 10006:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:493 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:507
__do_kmalloc mm/slab.c:3655 [inline]
__kmalloc+0x163/0x770 mm/slab.c:3664
kmalloc include/linux/slab.h:557 [inline]
hcd_buffer_alloc+0x1c6/0x260 drivers/usb/core/buffer.c:132
usb_alloc_coherent+0x62/0x90 drivers/usb/core/usb.c:910
usbdev_mmap+0x1ce/0x790 drivers/usb/core/devio.c:224
call_mmap include/linux/fs.h:1875 [inline]
mmap_region+0xc35/0x1760 mm/mmap.c:1788
do_mmap+0x82e/0x1090 mm/mmap.c:1561
do_mmap_pgoff include/linux/mm.h:2374 [inline]
vm_mmap_pgoff+0x1c5/0x230 mm/util.c:391
ksys_mmap_pgoff+0x4aa/0x630 mm/mmap.c:1611
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
__x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9516:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:455
kasan_slab_free+0xe/0x10 mm/kasan/common.c:463
__cache_free mm/slab.c:3425 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3756
tomoyo_init_log+0x15ba/0x2070 security/tomoyo/audit.c:293
tomoyo_supervisor+0x33f/0xef0 security/tomoyo/common.c:2095
tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
tomoyo_env_perm+0x18e/0x210 security/tomoyo/environ.c:63
tomoyo_environ security/tomoyo/domain.c:670 [inline]
tomoyo_find_next_domain+0x1354/0x1f6c security/tomoyo/domain.c:876
tomoyo_bprm_check_security security/tomoyo/tomoyo.c:107 [inline]
tomoyo_bprm_check_security+0x124/0x1b0 security/tomoyo/tomoyo.c:97
security_bprm_check+0x63/0xb0 security/security.c:750
search_binary_handler+0x71/0x570 fs/exec.c:1645
exec_binprm fs/exec.c:1701 [inline]
__do_execve_file.isra.0+0x1333/0x2340 fs/exec.c:1821
do_execveat_common fs/exec.c:1868 [inline]
do_execve fs/exec.c:1885 [inline]
__do_sys_execve fs/exec.c:1961 [inline]
__se_sys_execve fs/exec.c:1956 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1956
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888091e109c0
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2496 bytes to the left of
8192-byte region [ffff888091e109c0, ffff888091e129c0)
The buggy address belongs to the page:
page:ffffea0002478400 refcount:2 mapcount:0 mapping:ffff8880aa4021c0
index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000242e608 ffffea0002436708 ffff8880aa4021c0
raw: 0000000000000000 ffff888091e109c0 0000000200000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888091e0ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888091e0ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff888091e10000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff888091e10080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888091e10100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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