• H
    fs/ntfs3: Fix slab-out-of-bounds read in run_unpack · 887bfc54
    Hawkins Jiawei 提交于
    Syzkaller reports slab-out-of-bounds bug as follows:
    ==================================================================
    BUG: KASAN: slab-out-of-bounds in run_unpack+0x8b7/0x970 fs/ntfs3/run.c:944
    Read of size 1 at addr ffff88801bbdff02 by task syz-executor131/3611
    
    [...]
    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:317 [inline]
     print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
     kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
     run_unpack+0x8b7/0x970 fs/ntfs3/run.c:944
     run_unpack_ex+0xb0/0x7c0 fs/ntfs3/run.c:1057
     ntfs_read_mft fs/ntfs3/inode.c:368 [inline]
     ntfs_iget5+0xc20/0x3280 fs/ntfs3/inode.c:501
     ntfs_loadlog_and_replay+0x124/0x5d0 fs/ntfs3/fsntfs.c:272
     ntfs_fill_super+0x1eff/0x37f0 fs/ntfs3/super.c:1018
     get_tree_bdev+0x440/0x760 fs/super.c:1323
     vfs_get_tree+0x89/0x2f0 fs/super.c:1530
     do_new_mount fs/namespace.c:3040 [inline]
     path_mount+0x1326/0x1e20 fs/namespace.c:3370
     do_mount fs/namespace.c:3383 [inline]
     __do_sys_mount fs/namespace.c:3591 [inline]
     __se_sys_mount fs/namespace.c:3568 [inline]
     __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
     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
     [...]
     </TASK>
    
    The buggy address belongs to the physical page:
    page:ffffea00006ef600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1bbd8
    head:ffffea00006ef600 order:3 compound_mapcount:0 compound_pincount:0
    flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
    page dumped because: kasan: bad access detected
    
    Memory state around the buggy address:
     ffff88801bbdfe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88801bbdfe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    >ffff88801bbdff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                       ^
     ffff88801bbdff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88801bbe0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ==================================================================
    
    Kernel will tries to read record and parse MFT from disk in
    ntfs_read_mft().
    
    Yet the problem is that during enumerating attributes in record,
    kernel doesn't check whether run_off field loading from the disk
    is a valid value.
    
    To be more specific, if attr->nres.run_off is larger than attr->size,
    kernel will passes an invalid argument run_buf_size in
    run_unpack_ex(), which having an integer overflow. Then this invalid
    argument will triggers the slab-out-of-bounds Read bug as above.
    
    This patch solves it by adding the sanity check between
    the offset to packed runs and attribute size.
    
    link: https://lore.kernel.org/all/0000000000009145fc05e94bd5c3@google.com/#t
    Reported-and-tested-by: syzbot+8d6fbb27a6aded64b25b@syzkaller.appspotmail.com
    Signed-off-by: NHawkins Jiawei <yin31149@gmail.com>
    Signed-off-by: NKonstantin Komarov <almaz.alexandrovich@paragon-software.com>
    887bfc54
inode.c 48.5 KB