ntfs3: fix circular locking dependency in run_unpack_ex

Overview

In the Linux kernel, the following vulnerability has been resolved:

ntfs3: fix circular locking dependency in run_unpack_ex

Syzbot reported a circular locking dependency between wnd->rw_lock (sbi->used.bitmap) and ni->file.run_lock.

The deadlock scenario:

1. ntfs_extend_mft() takes ni->file.run_lock then wnd->rw_lock.
2. run_unpack_ex() takes wnd->rw_lock then tries to acquire ni->file.run_lock inside ntfs_refresh_zone().

This creates an AB-BA deadlock.

Fix this by using down_read_trylock() instead of down_read() when acquiring run_lock in run_unpack_ex(). If the lock is contended, skip ntfs_refresh_zone() - the MFT zone will be refreshed on the next MFT operation. This breaks the circular dependency since we never block waiting for run_lock while holding wnd->rw_lock.

Affected

• Linux >= 57f7979aefdcef66326bda47e07ee0d8be64bf21 < d60f09d2d16c44a797d8cb67015cde2508720506
• Linux >= db7fc56646cafe39599a4c21f1398e2bdfd5c185 < 76016d15bbd90caa0ce7765fddf9bde8e943e601
• Linux >= 5fc982fe7eca9d0cf7b25832450ebd4f7c8e1c36 < b014372b62237521444ee51384549bdf48b79015
• Linux >= 5fc982fe7eca9d0cf7b25832450ebd4f7c8e1c36 < b8d22d9d8260b0f4f4d8e2898c98037c9982ea66
• Linux >= 5fc982fe7eca9d0cf7b25832450ebd4f7c8e1c36 < 08ce2fee1b869ecbfbd94e0eb2630e52203a2e03
• Linux >= 6.6.66 < 6.6.160
• Linux >= 6.12.5 < 6.12.114
• Linux 6.13

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.