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CVE-2025-68823

ublk: fix deadlock when reading partition table PUBLISHED

Description (CNA)

In 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]

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 71f28f3136aff5890cd56de78abc673f8393cad9 before 27bb79b7717b2fbb111a1c13548b2786ee712dca; affected 71f28f3136aff5890cd56de78abc673f8393cad9 before 64c0b7e2293757e8320f13434cd809f1c9257a62; affected 71f28f3136aff5890cd56de78abc673f8393cad9 before 9bcc47343ee0ef346aa7b2b460c8ff56bd882fe7; affected 71f28f3136aff5890cd56de78abc673f8393cad9 before 0460e09a614291f06c008443f47393c37b7358e7; affected 71f28f3136aff5890cd56de78abc673f8393cad9 before c258f5c4502c9667bccf5d76fa731ab9c96687c1
Linux / Linuxaffected 6.0; unaffected 0 before 6.0; unaffected 6.1.175 through 6.1.*; unaffected 6.6.124 through 6.6.*; unaffected 6.12.70 through 6.12.*; unaffected 6.18.3 through 6.18.*; unaffected 6.19 through *

CWE

No CWE identifiers supplied.

References