Bug 2532420 (CVE-2026-89586) - CVE-2026-89586 kernel: ata: libata-scsi: fix DSM TRIM for sector sizes larger than 2048 bytes
Summary: CVE-2026-89586 kernel: ata: libata-scsi: fix DSM TRIM for sector sizes larger...
Keywords:
Status: NEW
Alias: CVE-2026-89586
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-11 22:55 UTC by OSIDB Bzimport
Modified: 2026-09-15 10:03 UTC (History)
17 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-09-11 22:55:29 UTC
In the Linux kernel, the following vulnerability has been resolved:

ata: libata-scsi: fix DSM TRIM for sector sizes larger than 2048 bytes

ata_scsi_write_same_xlat() translates a SCSI WRITE SAME command with the
UNMAP bit set into an ATA DATA SET MANAGEMENT TRIM command.  The TRIM
descriptor is built by ata_format_dsm_trim_descr() into the 2048-byte
ata_scsi_rbuf staging buffer, and the number of bytes copied is compared
against the logical sector size by the caller:

	size = ata_format_dsm_trim_descr(scmd, trmax, block, n_block);
	if (size != len)		/* len == sdp->sector_size */
		goto invalid_param_len;

ata_format_dsm_trim_descr() clamps the copy length to ATA_SCSI_RBUF_SIZE
(2048).  On a device whose logical sector size exceeds that (e.g. a 4Kn
device, where sector_size == 4096) the function can never return more than
2048, while the caller expects it to return sector_size.  The comparison
therefore always fails, so every TRIM is rejected with "Parameter list
length error" and WARN_ON() splats on each attempt.  TRIM / discard is
thus completely broken on such devices.

The descriptor was incorrectly sized from the logical sector size.  A DSM
TRIM payload is a list of 512-byte pages, each holding up to
ATA_MAX_TRIM_RNUM (64) LBA Range Entries, and is independent of the logical
sector size.  The Block Limits VPD page already advertises a single such
page as the maximum WRITE SAME length (65535 * ATA_MAX_TRIM_RNUM logical
blocks), so the block layer never sends a request that needs more than one
page.

Emit exactly one 512-byte page, independent of the logical sector size,
and transfer only that page (COUNT == 1).  For a 512-byte-sector device
this is unchanged; devices with larger logical sectors now work instead of
failing every TRIM.


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