CVE-2026-43127

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.