Medium [CVE-2026-53029] prevent uninitialized lcn caused by zero len
This medium-severity Red Hat Linux advisory covers CVE-2026-53029.
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Summary
In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: prevent uninitialized lcn caused by zero len syzbot reported a uninit-value in ntfs_iomap_begin [1]. Since runs was not touched yet, run_lookup_entry() immediately fails and returns false, which makes the value of "*len" 0.
Simultaneously, the new value and err value are also 0, causing the logic in attr_data_get_block_locked() to jump directly to ok, ultimately resulting in *lcn being triggered before it is set [1].
In ntfs_iomap_begin(), the check for a 0 value in clen is moved forward to before updating lcn to avoid this [1]. [1] BUG: KMSAN: uninit-value in ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825 ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825 iomap_iter+0x9b7/0x1540 fs/iomap/iter.c:110 Local variable lcn created at: ntfs_iomap_begin+0x15d/0x1460 fs/ntfs3/inode.c:786 A flaw was found in the Linux kernel's `ntfs3` filesystem driver.
This vulnerability occurs due to an uninitialized local variable (`lcn`) when handling zero-length data during I/O operations. An attacker could potentially exploit this flaw to cause a denial of service or information disclosure due to unpredictable behavior resulting from the use of uninitialized memory.
Red Hat severity: Moderate. Weakness: CWE-824.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
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