CVE-2026-93268 in Linux
Summary
by MITRE • 09/24/2026
In the Linux kernel, the following vulnerability has been resolved:
ext4: skip extra isize expansion during mount to prevent deadlock
ext4_try_to_expand_extra_isize() is called from __ext4_mark_inode_dirty() while holding an active jbd2 handle. During mount (!SB_ACTIVE), the expand path may move xattrs to external blocks and release ea_inodes via iput(). When !SB_ACTIVE, iput() calls write_inode_now() which acquires s_writepages_rwsem, creating a circular lock dependency:
s_writepages_rwsem --> jbd2_handle --> xattr_sem --> s_writepages_rwsem
This can be triggered via:
ext4_process_orphan() -> ext4_truncate() -> ext4_mark_inode_dirty() -> ext4_try_to_expand_extra_isize()
or:
ext4_evict_inode() -> ext4_mark_inode_dirty() -> ext4_try_to_expand_extra_isize()
Skip expansion when !SB_ACTIVE. This is a minor loss of functionality (extra isize won't grow for these inodes during mount), which e2fsck can resolve later if needed.
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