• E
    ext4: check bh in ext4_read_block_bitmap() · 15b49132
    Eryu Guan 提交于
    Validate the bh pointer before using it, since
    ext4_read_block_bitmap_nowait() might return NULL.
    
    I've seen this in fsfuzz testing.
    
     EXT4-fs error (device loop0): ext4_read_block_bitmap_nowait:385: comm touch: Cannot get buffer for block bitmap - block_group = 0, block_bitmap = 3925999616
     BUG: unable to handle kernel NULL pointer dereference at           (null)
     IP: [<ffffffff8121de25>] ext4_wait_block_bitmap+0x25/0xe0
     ...
     Call Trace:
      [<ffffffff8121e1e5>] ext4_read_block_bitmap+0x35/0x60
      [<ffffffff8125e9c6>] ext4_free_blocks+0x236/0xb80
      [<ffffffff811d0d36>] ? __getblk+0x36/0x70
      [<ffffffff811d0a5f>] ? __find_get_block+0x8f/0x210
      [<ffffffff81191ef3>] ? kmem_cache_free+0x33/0x140
      [<ffffffff812678e5>] ext4_xattr_release_block+0x1b5/0x1d0
      [<ffffffff812679be>] ext4_xattr_delete_inode+0xbe/0x100
      [<ffffffff81222a7c>] ext4_free_inode+0x7c/0x4d0
      [<ffffffff812277b8>] ? ext4_mark_inode_dirty+0x88/0x230
      [<ffffffff8122993c>] ext4_evict_inode+0x32c/0x490
      [<ffffffff811b8cd7>] evict+0xa7/0x1c0
      [<ffffffff811b8ed3>] iput_final+0xe3/0x170
      [<ffffffff811b8f9e>] iput+0x3e/0x50
      [<ffffffff812316fd>] ext4_add_nondir+0x4d/0x90
      [<ffffffff81231d0b>] ext4_create+0xeb/0x170
      [<ffffffff811aae9c>] vfs_create+0xac/0xd0
      [<ffffffff811ac845>] lookup_open+0x185/0x1c0
      [<ffffffff8129e3b9>] ? selinux_inode_permission+0xa9/0x170
      [<ffffffff811acb54>] do_last+0x2d4/0x7a0
      [<ffffffff811af743>] path_openat+0xb3/0x480
      [<ffffffff8116a8a1>] ? handle_mm_fault+0x251/0x3b0
      [<ffffffff811afc49>] do_filp_open+0x49/0xa0
      [<ffffffff811bbaad>] ? __alloc_fd+0xdd/0x150
      [<ffffffff8119da28>] do_sys_open+0x108/0x1f0
      [<ffffffff8119db51>] sys_open+0x21/0x30
      [<ffffffff81618959>] system_call_fastpath+0x16/0x1b
    
    Also fix comment for ext4_read_block_bitmap_nowait()
    Signed-off-by: NEryu Guan <guaneryu@gmail.com>
    Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
    Cc: stable@vger.kernel.org
    15b49132
balloc.c 23.1 KB