syzbot <syzbot+46f1dd7dbbe2bfb98b10@xxxxxxxxxxxxxxxxxxxxxxxxx> writes: > 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@xxxxxxxxxxxx> > 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@xxxxxxxxxxxxxxxxxxxxxxxxx > 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 Hm, the bisection seems bogus but the stack points us to the following piece of code: 4776) if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmptr), &map)) { <skip> 4783) return nested_vmx_failValid(vcpu, 4784) VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID); 4785) } 4786) 4787) new_vmcs12 = map.hva; 4788) *4789) if (new_vmcs12->hdr.revision_id != VMCS12_REVISION || 4790) (new_vmcs12->hdr.shadow_vmcs && 4791) !nested_cpu_has_vmx_shadow_vmcs(vcpu))) { the reported problem seems to be on VMCS12 region access but it's part of guest memory and we successfuly managed to map it. We're definitely within 1-page range. Maybe KASAN is just wrong here? -- Vitaly
