ublk: fix deadlock when reading partition table

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Summary

CVECVE-2025-68823
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-13 16:16:04 UTC
Updated2026-06-01 17:16:38 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ublk: fix deadlock when reading partition table When one process(such as udev) opens ublk block device (e.g., to read the partition table via bdev_open()), a deadlock[1] can occur: 1. bdev_open() grabs disk->open_mutex 2. The process issues read I/O to ublk backend to read partition table 3. In __ublk_complete_rq(), blk_update_request() or blk_mq_end_request() runs bio->bi_end_io() callbacks 4. If this triggers fput() on file descriptor of ublk block device, the work may be deferred to current task's task work (see fput() implementation) 5. This eventually calls blkdev_release() from the same context 6. blkdev_release() tries to grab disk->open_mutex again 7. Deadlock: same task waiting for a mutex it already holds The fix is to run blk_update_request() and blk_mq_end_request() with bottom halves disabled. This forces blkdev_release() to run in kernel work-queue context instead of current task work context, and allows ublk server to make forward progress, and avoids the deadlock. [axboe: rewrite comment in ublk]

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-667

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 71f28f3136aff5890cd56de78abc673f8393cad9 27bb79b7717b2fbb111a1c13548b2786ee712dca git Not specified
CNA Linux Linux affected 71f28f3136aff5890cd56de78abc673f8393cad9 64c0b7e2293757e8320f13434cd809f1c9257a62 git Not specified
CNA Linux Linux affected 71f28f3136aff5890cd56de78abc673f8393cad9 9bcc47343ee0ef346aa7b2b460c8ff56bd882fe7 git Not specified
CNA Linux Linux affected 71f28f3136aff5890cd56de78abc673f8393cad9 0460e09a614291f06c008443f47393c37b7358e7 git Not specified
CNA Linux Linux affected 71f28f3136aff5890cd56de78abc673f8393cad9 c258f5c4502c9667bccf5d76fa731ab9c96687c1 git Not specified
CNA Linux Linux affected 6.0 Not specified
CNA Linux Linux unaffected 6.0 semver Not specified
CNA Linux Linux unaffected 6.1.175 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.124 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.70 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.3 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c258f5c4502c9667bccf5d76fa731ab9c96687c1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/0460e09a614291f06c008443f47393c37b7358e7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/9bcc47343ee0ef346aa7b2b460c8ff56bd882fe7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/64c0b7e2293757e8320f13434cd809f1c9257a62 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/27bb79b7717b2fbb111a1c13548b2786ee712dca 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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