Bug 2536231 (CVE-2026-93057)

Summary:	CVE-2026-93057 kernel: scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR context
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel. When the Universal Flash Storage (UFS) tagset is quiesced during devfreq gear scaling, the Transmit Event Queue Tail Register (TX EQTR) can attempt memory allocations. If direct memory reclaim is triggered in this state, it can lead to a deadlock because I/O operations to the UFS device are required for reclaim/writeback, but the queue is quiesced. This can result in a system hang, causing a Denial of Service (DoS).	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 17:01:17 UTC

In the Linux kernel, the following vulnerability has been resolved:

scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR context

TX EQTR may run while devfreq gear scaling has quiesced the UFS
tagset. In that context, functions ufshcd_tx_eqtr(), __ufshcd_tx_eqtr()
and ufs_qcom_get_rx_fom() allocate memory with GFP_KERNEL. If direct
reclaim is triggered, reclaim/writeback can depend on I/O to UFS
device. Because the queue is quiesced, this can cause deadlock.

Use memalloc_noio_save/restore() in ufshcd_tx_eqtr() to cover all
allocations in the TX EQTR call tree, including:

 - params->eqtr_record in ufshcd_tx_eqtr()

 - eqtr_data in __ufshcd_tx_eqtr()

 - params in ufs_qcom_get_rx_fom()

This is preferred over tagging individual call sites with GFP_NOIO, as it
automatically covers any future allocations added anywhere in the call tree
without requiring each caller to be aware of this constraint.

[mkp: fix label as suggested by Bart]

Comment 1 gkamathe 2026-09-19 21:00:46 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93057.mbox