CVE-2025-71067

Unknown

Description

In the Linux kernel, the following vulnerability has been resolved: 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. [[email protected]: changed comment style, added return value handling]

SeverityUnknown
CVSS—
Exploit probability—
ProductLinux
PublishedJan 13, 2026
First seenJan 13, 2026

How to fix

Update
  • Linux Linux0c9327c8abf9c8f046e45008bb43d94d8ee5c6c5, 44a38eb4f7876513db5a1bccde74de9bc4389d43, 4fff9a625da958a33191c8553a03283786f9f417, b3c151fe8f543f1a0b8b5df16ce5d97afa5ec85a, d1693a7d5a38acf6424235a6070bcf5b186a360d or later

Affected products

ProductAffected versionsFixed in
Linux Linux28861e3bbd9e7ac4cd9c811aad71b4d116e27930 ≤ v < 0c9327c8abf9c8f046e45008bb43d94d8ee5c6c5, 28861e3bbd9e7ac4cd9c811aad71b4d116e27930 ≤ v < 44a38eb4f7876513db5a1bccde74de9bc4389d43, 28861e3bbd9e7ac4cd9c811aad71b4d116e27930 ≤ v < 4fff9a625da958a33191c8553a03283786f9f417, 28861e3bbd9e7ac4cd9c811aad71b4d116e27930 ≤ v < b3c151fe8f543f1a0b8b5df16ce5d97afa5ec85a, 28861e3bbd9e7ac4cd9c811aad71b4d116e27930 ≤ v < d1693a7d5a38acf6424235a6070bcf5b186a360d, 5.150c9327c8abf9c8f046e45008bb43d94d8ee5c6c5, 44a38eb4f7876513db5a1bccde74de9bc4389d43, 4fff9a625da958a33191c8553a03283786f9f417, b3c151fe8f543f1a0b8b5df16ce5d97afa5ec85a, d1693a7d5a38acf6424235a6070bcf5b186a360d

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