Hi, This seems non-exploitable due to mmap_min_addr, so I guess it should be treated just as a regular bug
Tested with 4.5-rc4 and with 4.4 under Opteron 6272 and FX-8320 [167193.153283] BUG: unable to handle kernel NULL pointer dereference at 00000000000000f0 [167193.153372] IP: [<ffffffffc0545067>] kvm_arch_vcpu_ioctl+0x417/0x1120 [kvm] [167193.153453] PGD fca0067 PUD 79907067 PMD 0 [167193.153503] Oops: 0000 [#1] SMP [167193.153571] Modules linked in: binfmt_misc nls_utf8 btrfs xor raid6_pq ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs libcrc32c kvm_amd amd64_edac_mod input_leds joydev kvm snd_pcm snd_timer edac_mce_amd edac_core snd i2c_piix4 irqbypass fam15h_power tpm_infineon shpchp k10temp crct10dif_pclmul crc32_pclmul aesni_intel psmouse evbug soundcore aes_x86_64 mac_hid lrw 8250_fintek gf128mul serio_raw glue_helper pcspkr ablk_helper cryptd ipmi_ssif ipmi_watchdog ipmi_si ipmi_poweroff ipmi_devintf ipmi_msghandler autofs4 pata_acpi hid_generic usbkbd usbmouse usbhid hid igb i2c_algo_bit dca ahci ptp pata_atiixp libahci pps_core fjes [167193.154119] CPU: 3 PID: 22154 Comm: z Not tainted 4.4.0-4-generic #19-Ubuntu [167193.154173] Hardware name: HP ProLiant DL165 G7, BIOS O37 02/02/2012 [167193.154224] task: ffff8801fe899b80 ti: ffff88005ff30000 task.ti: ffff88005ff30000 [167193.154304] RIP: 0010:[<ffffffffc0545067>] [<ffffffffc0545067>] kvm_arch_vcpu_ioctl+0x417/0x1120 [kvm] [167193.154397] RSP: 0018:ffff88005ff33d28 EFLAGS: 00010246 [167193.154445] RAX: 0000000000000000 RBX: ffffffffffffffea RCX: 0000000000000176 [167193.154523] RDX: 0000000000000000 RSI: 000000008040ae9f RDI: ffff880075eebe80 [167193.154601] RBP: ffff88005ff33e00 R08: 0000000000000000 R09: 0000000000000000 [167193.154684] R10: 0000000000000000 R11: 0000000000000212 R12: 0000000020010fef [167193.154785] R13: 0000000000000000 R14: ffff880075eebe80 R15: 0000000000000000 [167193.154864] FS: 00007f00c9d7b700(0000) GS:ffff88007dcc0000(0000) knlGS:0000000000000000 [167193.154945] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [167193.154994] CR2: 00000000000000f0 CR3: 0000000078982000 CR4: 00000000000406e0 [167193.155077] Stack: [167193.155112] ffffffff810e9ca1 0000000000000086 0000000050045e40 0000000000000003 [167193.155199] ffff880000105200 0000000000000000 0000000000000000 ffff880000000000 [167193.155286] ffff88005f000000 ffffffffc0249a63 0000000075eebe80 0000000050045e40 [167193.155373] Call Trace: [167193.155417] [<ffffffff810e9ca1>] ? add_timer_on+0xf1/0x160 [167193.155469] [<ffffffffc0249a63>] ? svm_vcpu_load+0x83/0x110 [kvm_amd] [167193.155536] [<ffffffffc0544a8a>] ? kvm_arch_vcpu_load+0x5a/0x220 [kvm] [167193.155600] [<ffffffffc0531de7>] kvm_vcpu_ioctl+0xe7/0x5f0 [kvm] [167193.155653] [<ffffffff81251952>] ? anon_inode_getfd+0x52/0x80 [167193.155713] [<ffffffffc0530db0>] ? kvm_dev_ioctl+0x140/0x4a0 [kvm] [167193.155766] [<ffffffff8121b108>] do_vfs_ioctl+0x298/0x480 [167193.155815] [<ffffffff81216e64>] ? putname+0x54/0x60 [167193.155863] [<ffffffff81206dbf>] ? do_sys_open+0x1bf/0x280 [167193.155913] [<ffffffff8121b369>] SyS_ioctl+0x79/0x90 [167193.155984] [<ffffffff81811f32>] entry_SYSCALL_64_fastpath+0x16/0x71 [167193.156035] Code: e0 01 83 e2 01 88 95 68 ff ff ff 41 0f b6 96 39 32 00 00 88 85 6a ff ff ff 88 95 69 ff ff ff 0f 1f 44 00 00 49 8b 86 a0 02 00 00 <48> 8b 80 f0 00 00 00 83 e0 01 88 85 6b ff ff ff c7 85 64 ff ff [167193.156326] RIP [<ffffffffc0545067>] kvm_arch_vcpu_ioctl+0x417/0x1120 [kvm] [167193.156391] RSP <ffff88005ff33d28> [167193.156432] CR2: 00000000000000f0 [167193.156840] ---[ end trace 3ff15297044194ff ]--- ==== // autogenerated by syzkaller (http://github.com/google/syzkaller) #include <unistd.h> #include <sys/syscall.h> #include <string.h> #include <stdint.h> #include <pthread.h> long r[6]; int main() { memset(r, -1, sizeof(r)); r[0] = syscall(SYS_mmap, 0x20000000ul, 0x13000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul); memcpy((void*)0x2000eedb, "\x2f\x64\x65\x76\x2f\x6b\x76\x6d", 8); r[2] = syscall(SYS_open, 0x2000eedbul, 0x0ul, 0x100ul, 0, 0, 0); r[3] = syscall(SYS_ioctl, r[2], 0xae01ul, 0x0ul, 0, 0, 0); r[4] = syscall(SYS_ioctl, r[3], 0xae41ul, 0x7ul, 0, 0, 0); r[5] = syscall(SYS_ioctl, r[4], 0x8040ae9ful, 0x20010feful, 0, 0, 0); return 0; } ==== strace: open("/dev/kvm", O_RDONLY) = 3 ioctl(3, KVM_CREATE_VM, 0) = 4 ioctl(4, KVM_CREATE_VCPU, 0x7) = 5 ioctl(5, KVM_GET_PIT2 or KVM_GET_VCPU_EVENTS, 0x20010fef) = 0 Should be run in parallel (try increasing 10 to 100 or so, if this doesn't work) $ for x in `seq 1 10`; do { ./prog & }; done -- Robert Święcki
