KASAN: use-after-free Read in shmem_fault

From: syzbot
Date: Sat Feb 16 2019 - 03:05:09 EST

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Hello,

syzbot found the following crash on:

HEAD commit: aa0c38cf39de Merge branch 'fixes' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146cadff400000
kernel config: https://syzkaller.appspot.com/x/.config?x=ee434566c893c7b1
dashboard link: https://syzkaller.appspot.com/bug?extid=56fbe62f8c55f860fd99
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+56fbe62f8c55f860fd99@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x30e0/0x4700 kernel/locking/lockdep.c:3215
Read of size 8 at addr ffff888098eda1a0 by task syz-executor.2/16643

CPU: 0 PID: 16643 Comm: syz-executor.2 Not tainted 5.0.0-rc6+ #68
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+0x7c/0x20d mm/kasan/report.c:187
kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
__lock_acquire+0x30e0/0x4700 kernel/locking/lockdep.c:3215
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3841
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
shmem_fault+0x5b4/0x760 mm/shmem.c:1972
__do_fault+0x116/0x4e0 mm/memory.c:3019
do_read_fault mm/memory.c:3430 [inline]
do_fault mm/memory.c:3556 [inline]
handle_pte_fault mm/memory.c:3787 [inline]
__handle_mm_fault+0x2cbd/0x3f20 mm/memory.c:3911
handle_mm_fault+0x43f/0xb30 mm/memory.c:3948
faultin_page mm/gup.c:535 [inline]
__get_user_pages+0x7b6/0x1a40 mm/gup.c:738
populate_vma_page_range+0x20d/0x2a0 mm/gup.c:1247
__mm_populate+0x204/0x380 mm/gup.c:1295
mm_populate include/linux/mm.h:2388 [inline]
vm_mmap_pgoff+0x213/0x230 mm/util.c:355
ksys_mmap_pgoff+0xf7/0x630 mm/mmap.c:1609
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
__x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e39
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe43bdebc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457e39
RDX: 0000000000000003 RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 000000000073bf00 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 00007fe43bdec6d4
R13: 00000000004c3b9e R14: 00000000004d6c88 R15: 00000000ffffffff

Allocated by task 16643:
save_stack+0x45/0xd0 mm/kasan/common.c:73
set_track mm/kasan/common.c:85 [inline]
__kasan_kmalloc mm/kasan/common.c:496 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
kasan_kmalloc mm/kasan/common.c:504 [inline]
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411
kmem_cache_alloc+0x12d/0x710 mm/slab.c:3543
shmem_alloc_inode+0x1c/0x50 mm/shmem.c:3544
alloc_inode+0x66/0x190 fs/inode.c:210
new_inode_pseudo+0x19/0xf0 fs/inode.c:906
new_inode+0x1f/0x40 fs/inode.c:935
shmem_get_inode+0x84/0x780 mm/shmem.c:2148
__shmem_file_setup.part.0+0x1e2/0x2b0 mm/shmem.c:3900
__shmem_file_setup mm/shmem.c:3894 [inline]
shmem_kernel_file_setup mm/shmem.c:3930 [inline]
shmem_zero_setup+0xe2/0x474 mm/shmem.c:3974
mmap_region+0x136c/0x1760 mm/mmap.c:1802
do_mmap+0x8e2/0x1080 mm/mmap.c:1559
do_mmap_pgoff include/linux/mm.h:2379 [inline]
vm_mmap_pgoff+0x1c5/0x230 mm/util.c:350
ksys_mmap_pgoff+0xf7/0x630 mm/mmap.c:1609
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
__x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
save_stack+0x45/0xd0 mm/kasan/common.c:73
set_track mm/kasan/common.c:85 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:458
kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
__cache_free mm/slab.c:3487 [inline]
kmem_cache_free+0x86/0x260 mm/slab.c:3749
shmem_destroy_callback+0x6e/0xc0 mm/shmem.c:3555
__rcu_reclaim kernel/rcu/rcu.h:240 [inline]
rcu_do_batch kernel/rcu/tree.c:2452 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
rcu_process_callbacks+0x928/0x1390 kernel/rcu/tree.c:2754
__do_softirq+0x266/0x95a kernel/softirq.c:292

The buggy address belongs to the object at ffff888098eda000
which belongs to the cache shmem_inode_cache(49:syz2) of size 1184
The buggy address is located 416 bytes inside of
1184-byte region [ffff888098eda000, ffff888098eda4a0)
The buggy address belongs to the page:
page:ffffea000263b680 count:1 mapcount:0 mapping:ffff888085ba8d80 index:0xffff888098edaffd
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000283a708 ffffea00029ce6c8 ffff888085ba8d80
raw: ffff888098edaffd ffff888098eda000 0000000100000001 ffff88805755e540
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88805755e540

Memory state around the buggy address:
ffff888098eda080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888098eda100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

ffff888098eda180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff888098eda200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888098eda280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Julia Lawall: "Re: [v5] Coccinelle: semantic code search for missing put_device()"
Previous message: Yao HongBo: "Re: possible deadlock in console_unlock"
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