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

From: syzbot
Date: Fri Apr 10 2020 - 12:33:14 EST

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Hello,

syzbot found the following crash on:

HEAD commit: f5e94d10 Merge tag 'drm-next-2020-04-08' of git://anongit...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1450c657e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ca75979eeebf06c2
dashboard link: https://syzkaller.appspot.com/bug?extid=25a50e1a4e196faed650
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+25a50e1a4e196faed650@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in search_memslots include/linux/kvm_host.h:1051 [inline]
BUG: KASAN: slab-out-of-bounds in __gfn_to_memslot include/linux/kvm_host.h:1063 [inline]
BUG: KASAN: slab-out-of-bounds in gfn_to_memslot arch/x86/kvm/../../../virt/kvm/kvm_main.c:1597 [inline]
BUG: KASAN: slab-out-of-bounds in gfn_to_pfn+0x4a6/0x4c0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1977
Read of size 8 at addr ffff88809ddb0468 by task syz-executor.2/22057

CPU: 1 PID: 22057 Comm: syz-executor.2 Not tainted 5.6.0-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+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
__kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
kasan_report+0x33/0x50 mm/kasan/common.c:625
search_memslots include/linux/kvm_host.h:1051 [inline]
__gfn_to_memslot include/linux/kvm_host.h:1063 [inline]
gfn_to_memslot arch/x86/kvm/../../../virt/kvm/kvm_main.c:1597 [inline]
gfn_to_pfn+0x4a6/0x4c0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1977
reexecute_instruction arch/x86/kvm/x86.c:6521 [inline]
reexecute_instruction+0x1fa/0x430 arch/x86/kvm/x86.c:6486
x86_emulate_instruction+0x880/0x1c50 arch/x86/kvm/x86.c:6795
kvm_mmu_page_fault+0x308/0x15d0 arch/x86/kvm/mmu/mmu.c:5495
vmx_handle_exit+0x2b8/0x1700 arch/x86/kvm/vmx/vmx.c:5953
vcpu_enter_guest+0xfea/0x59d0 arch/x86/kvm/x86.c:8470
vcpu_run arch/x86/kvm/x86.c:8533 [inline]
kvm_arch_vcpu_ioctl_run+0x3fb/0x16a0 arch/x86/kvm/x86.c:8755
kvm_vcpu_ioctl+0x493/0xe60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3138
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c889
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fdba05c4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdba05c56d4 RCX: 000000000045c889
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003be R14: 00000000004c64be R15: 000000000076bf0c

Allocated by task 22057:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
__kasan_kmalloc mm/kasan/common.c:495 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
kmalloc_node include/linux/slab.h:578 [inline]
kvmalloc_node+0x61/0xf0 mm/util.c:574
kvmalloc include/linux/mm.h:739 [inline]
kvzalloc include/linux/mm.h:747 [inline]
kvm_dup_memslots arch/x86/kvm/../../../virt/kvm/kvm_main.c:1101 [inline]
kvm_set_memslot+0x115/0x1530 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1118
__kvm_set_memory_region+0xcf7/0x1320 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1300
kvm_set_memory_region+0x29/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1321
kvm_vm_ioctl_set_memory_region arch/x86/kvm/../../../virt/kvm/kvm_main.c:1333 [inline]
kvm_vm_ioctl+0x678/0x23e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3604
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 21458:
save_stack+0x1b/0x40 mm/kasan/common.c:49
set_track mm/kasan/common.c:57 [inline]
kasan_set_free_info mm/kasan/common.c:317 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
kvfree+0x42/0x50 mm/util.c:603
__free_fdtable+0x2d/0x70 fs/file.c:31
put_files_struct fs/file.c:420 [inline]
put_files_struct+0x248/0x2e0 fs/file.c:413
exit_files+0x7e/0xa0 fs/file.c:445
do_exit+0xb04/0x2dd0 kernel/exit.c:790
do_group_exit+0x125/0x340 kernel/exit.c:893
get_signal+0x47b/0x24e0 kernel/signal.c:2739
do_signal+0x81/0x2240 arch/x86/kernel/signal.c:784
exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff88809ddb0000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1128 bytes inside of
2048-byte region [ffff88809ddb0000, ffff88809ddb0800)
The buggy address belongs to the page:
page:ffffea0002776c00 refcount:1 mapcount:0 mapping:00000000cff1b606 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00028d7ec8 ffffea00023c1148 ffff8880aa000e00
raw: 0000000000000000 ffff88809ddb0000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809ddb0300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88809ddb0380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809ddb0400: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
^
ffff88809ddb0480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809ddb0500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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Next message: Randy Dunlap: "Re: linux-next: Tree for Apr 10 (lib/test_printf.ko)"
Previous message: syzbot: "WARNING in hwsim_new_radio_nl"
Next in thread: Sean Christopherson: "Re: KASAN: slab-out-of-bounds Read in gfn_to_pfn"
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