[syzbot] KASAN: use-after-free Read in mtree_range_walk

From: syzbot
Date: Sat Oct 22 2022 - 06:09:33 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 4da34b7d175d Merge tag 'thermal-6.1-rc2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=162d61b4880000
kernel config: https://syzkaller.appspot.com/x/.config?x=ea03ca45176080bc
dashboard link: https://syzkaller.appspot.com/bug?extid=2b3d442b8ebfc7e50073
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/20d944930440/disk-4da34b7d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a40490d108a0/vmlinux-4da34b7d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2b3d442b8ebfc7e50073@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in mtree_range_walk+0x7b2/0x920 lib/maple_tree.c:2928
Read of size 8 at addr ffff88801fbb4a10 by task syz-executor.4/31718

CPU: 1 PID: 31718 Comm: syz-executor.4 Not tainted 6.1.0-rc1-syzkaller-00249-g4da34b7d175d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:395
kasan_report+0xbb/0x1f0 mm/kasan/report.c:495
mtree_range_walk+0x7b2/0x920 lib/maple_tree.c:2928
mas_state_walk lib/maple_tree.c:3843 [inline]
mt_find+0x463/0xee0 lib/maple_tree.c:6434
find_vma+0x108/0x1a0 mm/mmap.c:1835
do_user_addr_fault+0x2c1/0x1210 arch/x86/mm/fault.c:1389
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x94/0x170 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:fault_in_readable+0x175/0x290 mm/gup.c:1895
Code: 6f c9 ff 49 39 dd 0f 84 06 01 00 00 45 31 f6 eb 11 e8 6f 6f c9 ff 48 81 c3 00 10 00 00 4c 39 eb 74 1d e8 5e 6f c9 ff 45 89 f7 <8a> 03 31 ff 44 89 fe 88 44 24 28 e8 1b 6c c9 ff 45 85 ff 74 d2 e8
RSP: 0018:ffffc900056c7b18 EFLAGS: 00050246
RAX: 0000000000040000 RBX: 0000000020c53000 RCX: ffffc9000e3dc000
RDX: 0000000000040000 RSI: ffffffff81b31b92 RDI: 0000000000000005
RBP: 0000000020c52040 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000
R13: 0000000020c54000 R14: 0000000000000000 R15: 0000000000000000
fault_in_iov_iter_readable+0x24e/0x2c0 lib/iov_iter.c:356
generic_perform_write+0x1aa/0x570 mm/filemap.c:3743
__generic_file_write_iter+0x2aa/0x4d0 mm/filemap.c:3881
generic_file_write_iter+0xdf/0x350 mm/filemap.c:3913
call_write_iter include/linux/fs.h:2191 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:584
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7efff128b5f9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efff24c4168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007efff13abf80 RCX: 00007efff128b5f9
RDX: 00000000fffffeba RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007efff12e67b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efff18dfb1f R14: 00007efff24c4300 R15: 0000000000022000
</TASK>

Allocated by task 31739:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
kasan_set_track+0x21/0x30 mm/kasan/common.c:52
__kasan_slab_alloc+0x7e/0x80 mm/kasan/common.c:325
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slab.h:737 [inline]
kmem_cache_alloc_bulk+0x3e9/0x830 mm/slub.c:3854
mt_alloc_bulk lib/maple_tree.c:157 [inline]
mas_alloc_nodes+0x309/0x810 lib/maple_tree.c:1256
mas_node_count_gfp lib/maple_tree.c:1316 [inline]
mas_preallocate+0x1b7/0x360 lib/maple_tree.c:5719
__vma_adjust+0x18e/0x1ae0 mm/mmap.c:716
vma_adjust include/linux/mm.h:2663 [inline]
__split_vma+0x4b0/0x5c0 mm/mmap.c:2237
do_mas_align_munmap+0x54c/0xee0 mm/mmap.c:2362
do_mas_munmap+0x26a/0x2b0 mm/mmap.c:2502
do_munmap+0xc3/0x100 mm/mmap.c:2516
mremap_to mm/mremap.c:826 [inline]
__do_sys_mremap+0x12ce/0x16b0 mm/mremap.c:972
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 31715:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
kasan_set_track+0x21/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2a/0x40 mm/kasan/generic.c:511
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1750
slab_free mm/slub.c:3661 [inline]
kmem_cache_free_bulk.part.0+0x205/0x780 mm/slub.c:3779
mt_free_bulk lib/maple_tree.c:163 [inline]
mas_destroy+0x394/0x5c0 lib/maple_tree.c:5769
mas_store_prealloc+0xec/0x150 lib/maple_tree.c:5704
expand_downwards+0x962/0xdb0 mm/mmap.c:2066
do_user_addr_fault+0x901/0x1210 arch/x86/mm/fault.c:1400
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x94/0x170 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570

The buggy address belongs to the object at ffff88801fbb4a00
which belongs to the cache maple_node of size 256
The buggy address is located 16 bytes inside of
256-byte region [ffff88801fbb4a00, ffff88801fbb4b00)

The buggy address belongs to the physical page:
page:ffffea00007eed00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fbb4
head:ffffea00007eed00 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff88801184fdc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 31078, tgid 31078 (syz-executor.1), ts 1125816469332, free_ts 1109146474618
prep_new_page mm/page_alloc.c:2538 [inline]
get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4287
__alloc_pages+0x1c7/0x5a0 mm/page_alloc.c:5554
alloc_pages+0x1a6/0x270 mm/mempolicy.c:2285
alloc_slab_page mm/slub.c:1794 [inline]
allocate_slab+0x213/0x300 mm/slub.c:1939
new_slab mm/slub.c:1992 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3180
kmem_cache_alloc_bulk+0x28b/0x830 mm/slub.c:3830
mt_alloc_bulk lib/maple_tree.c:157 [inline]
mas_alloc_nodes+0x309/0x810 lib/maple_tree.c:1256
mas_node_count_gfp lib/maple_tree.c:1316 [inline]
mas_preallocate+0x1b7/0x360 lib/maple_tree.c:5719
vma_expand+0x1cc/0xb60 mm/mmap.c:542
mmap_region+0x131b/0x1c00 mm/mmap.c:2592
do_mmap+0x825/0xf50 mm/mmap.c:1412
vm_mmap_pgoff+0x1ab/0x270 mm/util.c:520
ksys_mmap_pgoff+0x41b/0x5a0 mm/mmap.c:1458
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1458 [inline]
free_pcp_prepare+0x65c/0xd90 mm/page_alloc.c:1508
free_unref_page_prepare mm/page_alloc.c:3386 [inline]
free_unref_page+0x19/0x4d0 mm/page_alloc.c:3482
kasan_depopulate_vmalloc_pte+0x5c/0x70 mm/kasan/shadow.c:372
apply_to_pte_range mm/memory.c:2640 [inline]
apply_to_pmd_range mm/memory.c:2684 [inline]
apply_to_pud_range mm/memory.c:2720 [inline]
apply_to_p4d_range mm/memory.c:2756 [inline]
__apply_to_page_range+0x68c/0x1030 mm/memory.c:2790
kasan_release_vmalloc+0xa7/0xc0 mm/kasan/shadow.c:486
__purge_vmap_area_lazy+0x885/0x1c50 mm/vmalloc.c:1770
drain_vmap_area_work+0x52/0xe0 mm/vmalloc.c:1799
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e4/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Memory state around the buggy address:
ffff88801fbb4900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801fbb4980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801fbb4a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801fbb4a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801fbb4b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 6f outsl %ds:(%rsi),(%dx)
1: c9 leaveq
2: ff 49 39 decl 0x39(%rcx)
5: dd 0f fisttpll (%rdi)
7: 84 06 test %al,(%rsi)
9: 01 00 add %eax,(%rax)
b: 00 45 31 add %al,0x31(%rbp)
e: f6 eb imul %bl
10: 11 e8 adc %ebp,%eax
12: 6f outsl %ds:(%rsi),(%dx)
13: 6f outsl %ds:(%rsi),(%dx)
14: c9 leaveq
15: ff 48 81 decl -0x7f(%rax)
18: c3 retq
19: 00 10 add %dl,(%rax)
1b: 00 00 add %al,(%rax)
1d: 4c 39 eb cmp %r13,%rbx
20: 74 1d je 0x3f
22: e8 5e 6f c9 ff callq 0xffc96f85
27: 45 89 f7 mov %r14d,%r15d
* 2a: 8a 03 mov (%rbx),%al <-- trapping instruction
2c: 31 ff xor %edi,%edi
2e: 44 89 fe mov %r15d,%esi
31: 88 44 24 28 mov %al,0x28(%rsp)
35: e8 1b 6c c9 ff callq 0xffc96c55
3a: 45 85 ff test %r15d,%r15d
3d: 74 d2 je 0x11
3f: e8 .byte 0xe8

---
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