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Date:   Fri, 14 Jul 2023 04:50:11 -0700
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Subject: [syzbot] [ext4?] KASAN: out-of-bounds Read in ext4_ext_remove_space
From:   syzbot <syzbot+6e5f2db05775244c73b7@syzkaller.appspotmail.com>
To:     adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com, tytso@mit.edu
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Hello,

syzbot found the following issue on:

HEAD commit:    06c2afb862f9 Linux 6.5-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d550a2a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=29fd3392a08741ef
dashboard link: https://syzkaller.appspot.com/bug?extid=6e5f2db05775244c73b7
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11fc4702a80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172a98eca80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b66ebf11f3d4/disk-06c2afb8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e277ce7d54f6/vmlinux-06c2afb8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5d0b981e9278/bzImage-06c2afb8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c48fda4748ae/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6e5f2db05775244c73b7@syzkaller.appspotmail.com

EXT4-fs error (device loop0) in ext4_mb_clear_bb:6537: Corrupt filesystem
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2736 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x2482/0x4d90 fs/ext4/extents.c:2958
Read of size 18446744073709551508 at addr ffff888073aea078 by task syz-executor420/6443

CPU: 1 PID: 6443 Comm: syz-executor420 Not tainted 6.5.0-rc1-syzkaller #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+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:475
 kasan_report+0x175/0x1b0 mm/kasan/report.c:588
 kasan_check_range+0x27e/0x290 mm/kasan/generic.c:187
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_ext_rm_leaf fs/ext4/extents.c:2736 [inline]
 ext4_ext_remove_space+0x2482/0x4d90 fs/ext4/extents.c:2958
 ext4_punch_hole+0x7a0/0xc10 fs/ext4/inode.c:3977
 ext4_fallocate+0x311/0x1f90 fs/ext4/extents.c:4706
 vfs_fallocate+0x551/0x6b0 fs/open.c:324
 do_vfs_ioctl+0x22cb/0x2b30 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x81/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff03605dce9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 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:00007ff02dc072f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff0360e27c0 RCX: 00007ff03605dce9
RDX: 0000000020000080 RSI: 000000004030582b RDI: 0000000000000004
RBP: 00007ff0360af678 R08: 00007ff02dc07700 R09: 0000000000000000
R10: 00007ff02dc07700 R11: 0000000000000246 R12: 65766f6365726f6e
R13: 0031656c69662f2e R14: 6f6f6c2f7665642f R15: 00007ff0360e27c8
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001ceba80 refcount:2 mapcount:0 mapping:ffff88801e21cd80 index:0x2b pfn:0x73aea
memcg:ffff888141652000
aops:def_blk_aops ino:700000
flags: 0xfff00000002036(referenced|uptodate|lru|active|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000002036 ffffea0001c164c8 ffffea0001f600c8 ffff88801e21cd80
raw: 000000000000002b ffff8880729c1d98 00000002ffffffff ffff888141652000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 6428, tgid 6426 (syz-executor420), ts 165572616396, free_ts 165556735464
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4477
 folio_alloc+0x1e/0x60 mm/mempolicy.c:2289
 filemap_alloc_folio+0xde/0x500 mm/filemap.c:979
 __filemap_get_folio+0x323/0xa00 mm/filemap.c:1933
 grow_dev_page fs/buffer.c:1063 [inline]
 grow_buffers fs/buffer.c:1123 [inline]
 __getblk_slow fs/buffer.c:1150 [inline]
 __getblk_gfp+0x218/0x630 fs/buffer.c:1445
 sb_getblk_gfp include/linux/buffer_head.h:376 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1334 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1435 [inline]
 ext4_ext_insert_extent+0xfe3/0x4e60 fs/ext4/extents.c:2102
 ext4_ext_map_blocks+0x1bdc/0x71d0 fs/ext4/extents.c:4306
 ext4_map_blocks+0xa2f/0x1cb0 fs/ext4/inode.c:621
 _ext4_get_block+0x238/0x6a0 fs/ext4/inode.c:763
 ext4_block_write_begin+0x53d/0x1570 fs/ext4/inode.c:1043
 ext4_write_begin+0x619/0x10b0
 ext4_da_write_begin+0x300/0xa40 fs/ext4/inode.c:2867
 generic_perform_write+0x31b/0x630 mm/filemap.c:3923
 ext4_buffered_write_iter+0xc6/0x350 fs/ext4/file.c:299
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1161 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2489
 release_pages+0x2193/0x2470 mm/swap.c:1042
 tlb_batch_pages_flush mm/mmu_gather.c:97 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
 tlb_flush_mmu+0x100/0x210 mm/mmu_gather.c:299
 tlb_finish_mmu+0xd4/0x1f0 mm/mmu_gather.c:391
 unmap_region+0x258/0x2a0 mm/mmap.c:2317
 do_vmi_align_munmap+0x135d/0x1630 mm/mmap.c:2556
 do_vmi_munmap+0x24d/0x2d0 mm/mmap.c:2623
 __vm_munmap+0x230/0x450 mm/mmap.c:2905
 __do_sys_munmap mm/mmap.c:2922 [inline]
 __se_sys_munmap mm/mmap.c:2919 [inline]
 __x64_sys_munmap+0x69/0x80 mm/mmap.c:2919
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff888073ae9f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888073ae9f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888073aea000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                                ^
 ffff888073aea080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888073aea100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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