Description

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.

Weaknesses 1

Affected Products 2

References 3

• git.kernel.org https://git.kernel.org/stable/c/08ce2fee1b869ecbfbd94e0eb2630e52203a2e03
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b014372b62237521444ee51384549bdf48b79015
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b8d22d9d8260b0f4f4d8e2898c98037c9982ea66
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/08ce2fee1b869ecbfbd94e0eb2630e52203a2e03
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b014372b62237521444ee51384549bdf48b79015
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b8d22d9d8260b0f4f4d8e2898c98037c9982ea66
  Patch