Hi all,
I have discovered a use-after-free issue in complete_emulated_mmio during kernel fuzz testing
with Syzkaller, the Call Trace is as follows:
Call Trace:
dump_stack+0xbe/0xfd
print_address_description.constprop.0+0x19/0x170
__kasan_report.cold+0x6c/0x84
kasan_report+0x3a/0x50
check_memory_region+0xfd/0x1f0
memcpy+0x20/0x60
complete_emulated_mmio+0x305/0x420
kvm_arch_vcpu_ioctl_run+0x63f/0x6d0
kvm_vcpu_ioctl+0x413/0xb20
__se_sys_ioctl+0x111/0x160
do_syscall_64+0x30/0x40
entry_SYSCALL_64_after_hwframe+0x67/0xd1
RIP: 0033:0x45570d
Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f93213e9048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000058c1f0 RCX: 000000000045570d
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 000000000058c1f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 0000000000425750 R15: 00007fff27f167f0
The buggy address belongs to the page:
page:000000005de3ae57 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111bff
flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff)
raw: 0017ffffc0000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888111bff780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888111bff800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888111bff880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888111bff900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888111bff980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Do you have any suggestions regarding this issue?
Any insights or debugging strategies would be greatly appreciated.
Thanks,
Dongjie Zou
