Message-ID: <0000000000003f1b8c06000ad675@google.com>
Date:   Sun, 09 Jul 2023 02:53:24 -0700
From:   syzbot <syzbot+c19a171264b968bf389b@...kaller.appspotmail.com>
To:     hdanton@...a.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] KASAN: slab-out-of-bounds Read in shrink_folio_list

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in shrink_folio_list

==================================================================
BUG: KASAN: slab-out-of-bounds in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: slab-out-of-bounds in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: slab-out-of-bounds in mapping_release_always include/linux/pagemap.h:279 [inline]
BUG: KASAN: slab-out-of-bounds in folio_needs_release mm/internal.h:187 [inline]
BUG: KASAN: slab-out-of-bounds in shrink_folio_list+0x2dbf/0x3e60 mm/vmscan.c:2067
Read of size 8 at addr ffff8880771f9411 by task syz-executor.0/5438

CPU: 0 PID: 5438 Comm: syz-executor.0 Not tainted 6.4.0-next-20230707-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:364
 print_report mm/kasan/report.c:475 [inline]
 kasan_report+0x11d/0x130 mm/kasan/report.c:588
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0xf0/0x190 mm/kasan/generic.c:187
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 mapping_release_always include/linux/pagemap.h:279 [inline]
 folio_needs_release mm/internal.h:187 [inline]
 shrink_folio_list+0x2dbf/0x3e60 mm/vmscan.c:2067
 reclaim_folio_list+0xd0/0x390 mm/vmscan.c:2801
 reclaim_pages+0x442/0x670 mm/vmscan.c:2837
 madvise_cold_or_pageout_pte_range+0x100e/0x1ee0 mm/madvise.c:533
 walk_pmd_range mm/pagewalk.c:140 [inline]
 walk_pud_range mm/pagewalk.c:218 [inline]
 walk_p4d_range mm/pagewalk.c:253 [inline]
 walk_pgd_range+0x9e7/0x1470 mm/pagewalk.c:290
 __walk_page_range+0x651/0x780 mm/pagewalk.c:392
 walk_page_range+0x311/0x4a0 mm/pagewalk.c:490
 madvise_pageout_page_range mm/madvise.c:591 [inline]
 madvise_pageout+0x2fe/0x560 mm/madvise.c:618
 madvise_vma_behavior+0x61a/0x21a0 mm/madvise.c:1039
 madvise_walk_vmas+0x1c7/0x2b0 mm/madvise.c:1268
 do_madvise.part.0+0x276/0x490 mm/madvise.c:1448
 do_madvise mm/madvise.c:1461 [inline]
 __do_sys_madvise mm/madvise.c:1461 [inline]
 __se_sys_madvise mm/madvise.c:1459 [inline]
 __x64_sys_madvise+0x117/0x150 mm/madvise.c:1459
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f09fd48c389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f09fe1fe168 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f09fd5abf80 RCX: 00007f09fd48c389
RDX: 0000000000000015 RSI: 0000000000600003 RDI: 0000000020000000
RBP: 00007f09fd4d7493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcb3184d8f R14: 00007f09fe1fe300 R15: 0000000000022000
 </TASK>

Allocated by task 5436:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 __kasan_slab_alloc+0x7f/0x90 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:186 [inline]
 slab_post_alloc_hook mm/slab.h:762 [inline]
 slab_alloc_node mm/slub.c:3470 [inline]
 slab_alloc mm/slub.c:3478 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3485 [inline]
 kmem_cache_alloc+0x173/0x390 mm/slub.c:3494
 anon_vma_alloc mm/rmap.c:94 [inline]
 __anon_vma_prepare+0x2c6/0x580 mm/rmap.c:203
 anon_vma_prepare include/linux/rmap.h:159 [inline]
 do_cow_fault mm/memory.c:4573 [inline]
 do_fault mm/memory.c:4682 [inline]
 do_pte_missing mm/memory.c:3673 [inline]
 handle_pte_fault mm/memory.c:4949 [inline]
 __handle_mm_fault+0x304a/0x3dd0 mm/memory.c:5089
 handle_mm_fault+0x2a1/0x9e0 mm/memory.c:5254
 do_user_addr_fault+0x435/0x10a0 arch/x86/mm/fault.c:1415
 handle_page_fault arch/x86/mm/fault.c:1509 [inline]
 exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1565
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

The buggy address belongs to the object at ffff8880771f9330
 which belongs to the cache anon_vma of size 208
The buggy address is located 17 bytes to the right of
 allocated 208-byte region [ffff8880771f9330, ffff8880771f9400)

The buggy address belongs to the physical page:
page:ffffea0001dc7e40 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880771f9aa0 pfn:0x771f9
memcg:ffff888015792801
ksm flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000200 ffff888014674140 ffffea00009b7300 0000000000000003
raw: ffff8880771f9aa0 00000000800f0009 00000001ffffffff ffff888015792801
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5394, tgid 5394 (dhcpcd-run-hook), ts 87861312397, free_ts 85675041379
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1569
 prep_new_page mm/page_alloc.c:1576 [inline]
 get_page_from_freelist+0xfd9/0x2c40 mm/page_alloc.c:3256
 __alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4512
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279
 alloc_slab_page mm/slub.c:1862 [inline]
 allocate_slab+0x25f/0x390 mm/slub.c:2009
 new_slab mm/slub.c:2062 [inline]
 ___slab_alloc+0xbc3/0x15d0 mm/slub.c:3215
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3314
 __slab_alloc_node mm/slub.c:3367 [inline]
 slab_alloc_node mm/slub.c:3460 [inline]
 slab_alloc mm/slub.c:3478 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3485 [inline]
 kmem_cache_alloc+0x371/0x390 mm/slub.c:3494
 anon_vma_alloc mm/rmap.c:94 [inline]
 anon_vma_fork+0xe2/0x630 mm/rmap.c:361
 dup_mmap+0xc0f/0x14b0 kernel/fork.c:734
 dup_mm kernel/fork.c:1696 [inline]
 copy_mm kernel/fork.c:1745 [inline]
 copy_process+0x6663/0x75c0 kernel/fork.c:2511
 kernel_clone+0xeb/0x890 kernel/fork.c:2919
 __do_sys_clone+0xba/0x100 kernel/fork.c:3062
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 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:1160 [inline]
 free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2383
 free_unref_page+0x33/0x370 mm/page_alloc.c:2478
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x195/0x220 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x63/0x90 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:186 [inline]
 slab_post_alloc_hook mm/slab.h:762 [inline]
 slab_alloc_node mm/slub.c:3470 [inline]
 kmem_cache_alloc_node+0x1cd/0x3f0 mm/slub.c:3515
 __alloc_skb+0x288/0x330 net/core/skbuff.c:634
 alloc_skb include/linux/skbuff.h:1289 [inline]
 alloc_skb_with_frags+0x9a/0x6f0 net/core/skbuff.c:6228
 sock_alloc_send_pskb+0x7a7/0x930 net/core/sock.c:2782
 unix_dgram_sendmsg+0x422/0x1b70 net/unix/af_unix.c:1944
 sock_sendmsg_nosec net/socket.c:725 [inline]
 sock_sendmsg+0xde/0x190 net/socket.c:748
 sock_write_iter+0x29b/0x3d0 net/socket.c:1129
 call_write_iter include/linux/fs.h:1873 [inline]
 do_iter_readv_writev+0x211/0x3b0 fs/read_write.c:735
 do_iter_write+0x182/0x810 fs/read_write.c:860
 vfs_writev+0x1b0/0x670 fs/read_write.c:933
 do_writev+0x270/0x2f0 fs/read_write.c:976

Memory state around the buggy address:
 ffff8880771f9300: fc fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00
 ffff8880771f9380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880771f9400: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
                         ^
 ffff8880771f9480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880771f9500: 00 00 fc fc fc fc fc fc fc fc 00 00 00 00 00 00
==================================================================


Tested on:

commit:         123212f5 Add linux-next specific files for 20230707
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16fb0fe2a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=15ec80b62f588543
dashboard link: https://syzkaller.appspot.com/bug?extid=c19a171264b968bf389b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=153c3fa0a80000

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