Message-ID: <000000000000830d1205cf7f0477@google.com>
Date:   Fri, 29 Oct 2021 07:55:27 -0700
From:   syzbot <syzbot+63d688f1d899c588fb71@...kaller.appspotmail.com>
To:     chao@...nel.org, gaoxiang25@...wei.com, gregkh@...uxfoundation.org,
        linux-erofs@...ts.ozlabs.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        viro@...iv.linux.org.uk, xiang@...nel.org, yuchao0@...wei.com
Subject: [syzbot] KASAN: use-after-free Read in LZ4_decompress_safe_partial

Hello,

syzbot found the following issue on:

HEAD commit:    87066fdd2e30 Revert "mm/secretmem: use refcount_t instead ..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c2c88cb00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=59f3ef2b4077575
dashboard link: https://syzkaller.appspot.com/bug?extid=63d688f1d899c588fb71
compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17032c4ab00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=170f8c3cb00000

The issue was bisected to:

commit f86cf25a609107960cf05263e491463feaae1f99
Author: Gao Xiang <gaoxiang25@...wei.com>
Date:   Tue Aug 28 03:39:48 2018 +0000

    Revert "staging: erofs: disable compiling temporarile"

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11de0328b00000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13de0328b00000
console output: https://syzkaller.appspot.com/x/log.txt?x=15de0328b00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+63d688f1d899c588fb71@...kaller.appspotmail.com
Fixes: f86cf25a6091 ("Revert "staging: erofs: disable compiling temporarile"")

==================================================================
BUG: KASAN: use-after-free in get_unaligned_le16 include/asm-generic/unaligned.h:27 [inline]
BUG: KASAN: use-after-free in LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline]
BUG: KASAN: use-after-free in LZ4_decompress_generic lib/lz4/lz4_decompress.c:285 [inline]
BUG: KASAN: use-after-free in LZ4_decompress_safe_partial+0xff8/0x1580 lib/lz4/lz4_decompress.c:469
Read of size 2 at addr ffff88806dd1f000 by task kworker/u5:0/150

CPU: 1 PID: 150 Comm: kworker/u5:0 Not tainted 5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: erofs_unzipd z_erofs_decompressqueue_work
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
 print_address_description+0x66/0x3e0 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report+0x19a/0x1f0 mm/kasan/report.c:459
 get_unaligned_le16 include/asm-generic/unaligned.h:27 [inline]
 LZ4_readLE16 lib/lz4/lz4defs.h:132 [inline]
 LZ4_decompress_generic lib/lz4/lz4_decompress.c:285 [inline]
 LZ4_decompress_safe_partial+0xff8/0x1580 lib/lz4/lz4_decompress.c:469
 z_erofs_lz4_decompress+0x4c3/0x1100 fs/erofs/decompressor.c:226
 z_erofs_decompress_generic fs/erofs/decompressor.c:354 [inline]
 z_erofs_decompress+0xa8e/0xe30 fs/erofs/decompressor.c:407
 z_erofs_decompress_pcluster+0x15e4/0x2550 fs/erofs/zdata.c:977
 z_erofs_decompress_queue fs/erofs/zdata.c:1055 [inline]
 z_erofs_decompressqueue_work+0x123/0x1a0 fs/erofs/zdata.c:1066
 process_one_work+0x853/0x1140 kernel/workqueue.c:2297
 worker_thread+0xac1/0x1320 kernel/workqueue.c:2444
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

The buggy address belongs to the page:
page:ffffea0001b747c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x6dd1f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001b74408 ffffea0001b74ac8 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 6527, ts 51734930672, free_ts 51749499849
 prep_new_page mm/page_alloc.c:2424 [inline]
 get_page_from_freelist+0x779/0xa30 mm/page_alloc.c:4153
 __alloc_pages+0x255/0x580 mm/page_alloc.c:5375
 alloc_pages_vma+0x668/0x1030 mm/mempolicy.c:2152
 do_anonymous_page+0x31b/0x14b0 mm/memory.c:3768
 handle_pte_fault mm/memory.c:4557 [inline]
 __handle_mm_fault mm/memory.c:4694 [inline]
 handle_mm_fault+0x1860/0x2560 mm/memory.c:4792
 do_user_addr_fault+0x8ce/0x10c0 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1485 [inline]
 exc_page_fault+0xa1/0x1e0 arch/x86/mm/fault.c:1541
 asm_exc_page_fault+0x1e/0x30
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1338 [inline]
 free_pcp_prepare+0xc29/0xd20 mm/page_alloc.c:1389
 free_unref_page_prepare mm/page_alloc.c:3315 [inline]
 free_unref_page_list+0x11f/0xa50 mm/page_alloc.c:3431
 release_pages+0x18cb/0x1b00 mm/swap.c:963
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
 tlb_flush_mmu+0x780/0x910 mm/mmu_gather.c:249
 tlb_finish_mmu+0xcb/0x200 mm/mmu_gather.c:340
 exit_mmap+0x3dd/0x6f0 mm/mmap.c:3173
 __mmput+0x111/0x3a0 kernel/fork.c:1115
 exec_mmap+0x53e/0x640 fs/exec.c:1030
 begin_new_exec+0x6c9/0x1180 fs/exec.c:1288
 load_elf_binary+0x836/0x3bc0 fs/binfmt_elf.c:1001
 search_binary_handler fs/exec.c:1725 [inline]
 exec_binprm fs/exec.c:1766 [inline]
 bprm_execve+0x8eb/0x1470 fs/exec.c:1835
 do_execveat_common+0x44c/0x590 fs/exec.c:1924
 do_execve fs/exec.c:1992 [inline]
 __do_sys_execve fs/exec.c:2068 [inline]
 __se_sys_execve fs/exec.c:2063 [inline]
 __x64_sys_execve+0x8e/0xa0 fs/exec.c:2063
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff88806dd1ef00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806dd1ef80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806dd1f000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88806dd1f080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806dd1f100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

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