diff options
| author | Pedro Demarchi Gomes <pedrodemargomes@gmail.com> | 2025-10-03 12:38:50 -0300 |
|---|---|---|
| committer | Konstantin Komarov <almaz.alexandrovich@paragon-software.com> | 2025-11-10 14:30:11 +0100 |
| commit | d1693a7d5a38acf6424235a6070bcf5b186a360d (patch) | |
| tree | 74d9ad0972de18fc3a7d3d5dd17c8e0fee2dce21 | |
| parent | 1ff28f36eb2f3b22b07c4f233f01b3a166108d1c (diff) | |
ntfs: set dummy blocksize to read boot_block when mounting
When mounting, sb->s_blocksize is used to read the boot_block without
being defined or validated. Set a dummy blocksize before attempting to
read the boot_block.
The issue can be triggered with the following syz reproducer:
mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0)
r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0)
ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000)
mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00',
&(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0)
syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0)
Here, the ioctl sets the bdev block size to 16384. During mount,
get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)),
but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves
sb->s_blocksize at zero.
Later, ntfs_init_from_boot() attempts to read the boot_block while
sb->s_blocksize is still zero, which triggers the bug.
Reported-by: syzbot+f4f84b57a01d6b8364ad@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f4f84b57a01d6b8364ad
Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
[almaz.alexandrovich@paragon-software.com: changed comment style, added
return value handling]
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
| -rw-r--r-- | fs/ntfs3/super.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index aae1f32f4dab..a478ec510640 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -946,6 +946,11 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size, sbi->volume.blocks = dev_size >> PAGE_SHIFT; + /* Set dummy blocksize to read boot_block. */ + if (!sb_min_blocksize(sb, PAGE_SIZE)) { + return -EINVAL; + } + read_boot: bh = ntfs_bread(sb, boot_block); if (!bh) |