Hello,
syzbot found the following crash on:
HEAD commit: d573e8a7 Linux 4.19.75
git tree: linux-4.19.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=13539d03600000
kernel config:
https://syzkaller.appspot.com/x/.config?x=50b385e67c7b7cdf
dashboard link:
https://syzkaller.appspot.com/bug?extid=88ca9093220c4af4d216
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=15d4bee9600000
C reproducer:
https://syzkaller.appspot.com/x/repro.c?x=148e6b45600000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by:
syzbot+88ca90...@syzkaller.appspotmail.com
audit: type=1400 audit(1569223609.146:36): avc: denied { map } for
pid=7447 comm="syz-executor465" path="/root/syz-executor465046457"
dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
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: null-ptr-deref in memset include/linux/string.h:333 [inline]
BUG: KASAN: null-ptr-deref in kvm_write_guest_virt_system+0x64/0x90
arch/x86/kvm/x86.c:5025
Write of size 24 at addr 0000000000000000 by task syz-executor465/7447
CPU: 1 PID: 7447 Comm: syz-executor465 Not tainted 4.19.75 #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
kasan_report_error mm/kasan/report.c:352 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x199/0x2ba mm/kasan/report.c:396
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
memset+0x24/0x40 mm/kasan/kasan.c:285
memset include/linux/string.h:333 [inline]
kvm_write_guest_virt_system+0x64/0x90 arch/x86/kvm/x86.c:5025
handle_vmread+0x7fe/0xa10 arch/x86/kvm/vmx.c:8802
vmx_handle_exit+0x276/0x16b0 arch/x86/kvm/vmx.c:10183
vcpu_enter_guest+0x10ca/0x5ed0 arch/x86/kvm/x86.c:7743
vcpu_run arch/x86/kvm/x86.c:7806 [inline]
kvm_arch_vcpu_ioctl_run+0x457/0x16b0 arch/x86/kvm/x86.c:8006
kvm_vcpu_ioctl+0x4dc/0xf90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2617
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x443679
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 1b 0c fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe01fbb3e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffe01fbb3f0 RCX: 0000000000443679
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000400f60 R09: 0000000000400f60
R10: 0000000020003800 R11: 0000000000000246 R12: 0000000000404720
R13: 00000000004047b0 R14: 0000000000000000 R15: 0000000000000000
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches