On 09/07/2013 05:32 PM, Sasha Levin wrote:
> Hi all,
>
> While fuzzing with trinity inside a KVM tools guest, running latest
> -next kernel, I've
> stumbled on the following:
>
> The disassembly is:
>
> /* Check the cache first. */
> /* (Cache hit rate is typically around 35%.) */
> vma = ACCESS_ONCE(mm->mmap_cache);
> 1f9: 48 8b 47 10 mov 0x10(%rdi),%rax
> if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
> 1fd: 48 85 c0 test %rax,%rax
> 200: 74 0b je 20d <find_vma+0x1d>
> 202: 48 39 70 08 cmp %rsi,0x8(%rax) <--- here
> 206: 76 05 jbe 20d <find_vma+0x1d>
> 208: 48 3b 30 cmp (%rax),%rsi
> 20b: 73 4d jae 25a <find_vma+0x6a>
I may have hit the same thing earlier this morning:
191: 48 8b 47 08 mov 0x8(%rdi),%rax
195: 31 d2 xor %edx,%edx
197: 48 85 c0 test %rax,%rax
19a: 74 1c je 1b8 <find_vma+0x3f>
19c: 48 39 70 e8 cmp %rsi,-0x18(%rax) <-- here
1a0: 76 10 jbe 1b2 <find_vma+0x39>
1a2: 48 39 70 e0 cmp %rsi,-0x20(%rax)
1a6: 48 8d 50 e0 lea -0x20(%rax),%rdx
1aa: 76 14 jbe 1c0 <find_vma+0x47>
Except I got there via munmap():
Sep 18 04:58:04 kernel: [563331.669009] CPU: 0 PID: 3937 Comm: Xorg Not
tainted 3.11.0-rc6-dan #1
Sep 18 04:58:04 kernel: [563331.669009] Hardware name: Gigabyte
Technology Co., Ltd. GA-MA78GPM-DS2H/GA-MA78GPM-DS2H, BIOS F6h 12/25/2010
Sep 18 04:58:04 kernel: [563331.669009] task: ffff88021d8f9700 ti:
ffff88021d66a000 task.ti: ffff88021d66a000 Sep 18 04:58:04 kernel:
[563331.669009] RIP: 0010:[<ffffffff810e9305>] [<ffffffff810e9305>]
find_vma+0x23/0x50
Sep 18 04:58:04 kernel: [563331.669009] RSP: 0018:ffff88021d66bed0
EFLAGS: 00010206
Sep 18 04:58:04 kernel: [563331.669009] RAX: 00ff8801e8e00ba0 RBX:
ffff880212a3f0c0 RCX: 0000000000000000
Sep 18 04:58:04 kernel: [563331.669009] RDX: ffff8801ae075f18 RSI:
00007feef8258000 RDI: ffff880212a3f0c0
Sep 18 04:58:04 kernel: [563331.669009] RBP: ffff88021d66bed0 R08:
0000000000000000 R09: 00000000000000d1
Sep 18 04:58:04 kernel: [563331.669009] R10: 0000000000000000 R11:
0000000000000206 R12: ffff880212a3f0c0
Sep 18 04:58:04 kernel: [563331.669009] R13: 00007feef8258000 R14:
0000000000001000 R15: 00007feef8258000
Sep 18 04:58:04 kernel: [563331.669009] FS: 00007feefe54b880(0000)
GS:ffff880227c00000(0000) knlGS:00000000f2640980
Sep 18 04:58:04 kernel: [563331.669009] CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
Sep 18 04:58:04 kernel: [563331.669009] CR2: 00007feef7486000 CR3:
00000002113d3000 CR4: 00000000000007f0
Sep 18 04:58:04 kernel: [563331.669009] Stack:
Sep 18 04:58:04 kernel: [563331.669009] ffff88021d66bf20
ffffffff810eace0 ffff88021e23a420 ffff88021b411600
Sep 18 04:58:04 kernel: [563331.669009] 00007feef8258000
ffff880212a3f110 ffff880212a3f0c0 00007feef8258000
Sep 18 04:58:04 kernel: [563331.669009] 0000000000001000
000000000000002f ffff88021d66bf58 ffffffff810eaf1e
Sep 18 04:58:04 kernel: [563331.669009] Call Trace:
Sep 18 04:58:04 kernel: [563331.669009] [<ffffffff810eace0>]
do_munmap+0xdd/0x2de
Sep 18 04:58:04 kernel: [563331.669009] [<ffffffff810eaf1e>]
vm_munmap+0x3d/0x56
Sep 18 04:58:04 kernel: [563331.669009] [<ffffffff810eaf55>]
SyS_munmap+0x1e/0x24
Sep 18 04:58:04 kernel: [563331.669009] [<ffffffff81549e96>]
system_call_fastpath+0x1a/0x1f
Sep 18 04:58:04 kernel: [563331.669009] Code: 85 c9 74 cb eb e4 5d c3 48
8b 47 10 55 48 89 e5 48 85 c0 74 0b 48 39 70 08 76 05 48 39 30 76 36 48
8b 47 08 31 d2 48 85 c0 74 1c <48> 39 70 e8 76 10 48 39 70 e0 48 8d 50
e0 76 14 48 8b 40 10 eb
Sep 18 04:58:04 kernel: [563331.669009] RIP [<ffffffff810e9305>]
find_vma+0x23/0x50
Sep 18 04:58:04 kernel: [563331.669009] RSP <ffff88021d66bed0>
Sep 18 04:58:04 kernel: [563331.690510] ---[ end trace 0b78e99bd4849eb8 ]---
This is possibly related, same machine, same path, same origin (Xorg,
probably cookie clicker causing lots of allocation churn on both bugs)
but an older kernel:
Sep 11 13:17:33 kernel: [12808122.743464] general protection fault: 0000
[#3] PREEMPT SMP
Sep 11 13:17:33 kernel: [12808122.746610] Modules linked in: uvcvideo
videobuf2_vmalloc videobuf2_memops videobuf2_core videodev iptable_nat
nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack
ip_tables x_tables pl2303 usbserial nfnetlink_queue nfnetlink_log ntfs
msdos reiserfs ext4 jbd2 ext3 jbd fuse arc4 ecb md4 sha256_generic
nls_utf8 cifs fscache cdc_acm efivars nls_cp437 vfat fat sg usb_storage
binfmt_misc rpcsec_gss_krb5 it87 hwmon_vid loop hid_generic
snd_hda_codec_hdmi snd_hda_codec_realtek powernow_k8 kvm_amd kvm pcspkr
k8temp snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc
snd_seq snd_seq_device snd_timer i2c_piix4 rtc_cmos radeon snd
drm_kms_helper ehci_pci ttm drm backlight i2c_algo_bit i2c_core wmi
soundcore ide_pci_generic atiixp ide_core firewire_ohci firewire_core
pata_acpi ohci_hcd ehci_hcd
Sep 11 13:17:33 kernel: [12808122.751214] CPU 1
Sep 11 13:17:33 kernel: [12808122.751214] Pid: 5692, comm: Xorg Tainted:
G D 3.9.0-rc7-dan #6 Gigabyte Technology Co., Ltd.
GA-MA78GPM-DS2H/GA-MA78GPM-DS2H
Sep 11 13:17:33 kernel: [12808122.751214] RIP: 0010:[<ffffffff812abc64>]
[<ffffffff812abc64>] __rb_erase_color+0x148/0x215
Sep 11 13:17:33 kernel: [12808122.751214] RSP: 0018:ffff880208529e58
EFLAGS: 00010206
Sep 11 13:17:33 kernel: [12808122.751214] RAX: 00ff88021df483b8 RBX:
ffff88015c87d248 RCX: ffff88015c87d450
Sep 11 13:17:33 kernel: [12808122.751214] RDX: 0000000000000000 RSI:
ffff8802080f5048 RDI: ffff88015c87d248
Sep 11 13:17:33 kernel: [12808122.751214] RBP: ffff880208529e80 R08:
ffff88015c87d238 R09: 0000000000003bd0
Sep 11 13:17:33 kernel: [12808122.751214] R10: 0000000000000000 R11:
0000000000003206 R12: ffff88015c87d978
Sep 11 13:17:33 kernel: [12808122.751214] R13: ffff88015c87d450 R14:
ffff8802080f5048 R15: ffffffff810de579
Sep 11 13:17:33 kernel: [12808122.751214] FS: 00007f7041814880(0000)
GS:ffff880227d00000(0000) knlGS:00000000f4285980
Sep 11 13:17:33 kernel: [12808122.751214] CS: 0010 DS: 0000 ES: 0000
CR0: 0000000080050033
Sep 11 13:17:33 kernel: [12808122.751214] CR2: 00007f703b2c0000 CR3:
000000014db58000 CR4: 00000000000007e0
Sep 11 13:17:33 kernel: [12808122.751214] DR0: 0000000000000000 DR1:
0000000000000000 DR2: 0000000000000000
Sep 11 13:17:33 kernel: [12808122.751214] DR3: 0000000000000000 DR6:
00000000ffff0ff0 DR7: 0000000000000400
Sep 11 13:17:33 kernel: [12808122.751214] Process Xorg (pid: 5692,
threadinfo ffff880208528000, task ffff880208079700)
Sep 11 13:17:33 kernel: [12808122.751214] Stack:
Sep 11 13:17:33 kernel: [12808122.751214] ffff88015c87d248
ffff88015c87d248 ffff88015c87d450 00007f703b5b4000
Sep 11 13:17:33 kernel: [12808122.751214] ffff88015c87d450
ffff880208529ec8 ffffffff810ded2f 0000000000000009
Sep 11 13:17:33 kernel: [12808122.751214] ffff8802080f5048
ffff8802080f5040 ffff88015c87d228 ffff88015c87d450
Sep 11 13:17:33 kernel: [12808122.751214] Call Trace:
Sep 11 13:17:33 kernel: [12808122.751214] [<ffffffff810ded2f>]
vma_rb_erase+0x1b5/0x1c2
Sep 11 13:17:33 kernel: [12808122.751214] [<ffffffff810e012c>]
do_munmap+0x1f0/0x31d
Sep 11 13:17:33 kernel: [12808122.751214] [<ffffffff810e0296>]
vm_munmap+0x3d/0x56
Sep 11 13:17:33 kernel: [12808122.751214] [<ffffffff810e02cd>]
sys_munmap+0x1e/0x24
Sep 11 13:17:33 kernel: [12808122.751214] [<ffffffff81527dd6>]
system_call_fastpath+0x1a/0x1f
Sep 11 13:17:33 kernel: [12808122.751214] Code: 48 39 58 10 75 06 4c 89
60 10 eb 09 4c 89 60 08 eb 03 4d 89 26 4c 89 e6 4d 89 ec 48 89 df 41 ff
d7 49 8b 44 24 10 48 85 c0 74 05 <f6> 00 01 74 66 4d 8b 6c 24 08 4d 85
ed 74 07 41 f6 45 00 01 74
Sep 11 13:17:33 kernel: [12808122.751214] RIP [<ffffffff812abc64>]
__rb_erase_color+0x148/0x215
Sep 11 13:17:33 kernel: [12808122.751214] RSP <ffff880208529e58>
Sep 11 13:17:33 kernel: [12808122.920434] ---[ end trace
8913f036c5b4f342 ]---
Unfortunately I don't have the 3.9 build directory anymore, but here's a
reconstruction:
void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
...
/usr/src/3.9/lib/rbtree.c:322
if (!tmp1 || rb_is_black(tmp1)) {
13a: 48 85 c0 test %rax,%rax
13d: 74 05 je 144 <__rb_erase_color+0x144>
13f: f6 00 01 testb $0x1,(%rax)
Both of mine look like current->mm is getting clobbered somewhere.
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