CVE-2025-39792
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-12

Last updated on: 2025-11-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: dm: Always split write BIOs to zoned device limits Any zoned DM target that requires zone append emulation will use the block layer zone write plugging. In such case, DM target drivers must not split BIOs using dm_accept_partial_bio() as doing so can potentially lead to deadlocks with queue freeze operations. Regular write operations used to emulate zone append operations also cannot be split by the target driver as that would result in an invalid writen sector value return using the BIO sector. In order for zoned DM target drivers to avoid such incorrect BIO splitting, we must ensure that large BIOs are split before being passed to the map() function of the target, thus guaranteeing that the limits for the mapped device are not exceeded. dm-crypt and dm-flakey are the only target drivers supporting zoned devices and using dm_accept_partial_bio(). In the case of dm-crypt, this function is used to split BIOs to the internal max_write_size limit (which will be suppressed in a different patch). However, since crypt_alloc_buffer() uses a bioset allowing only up to BIO_MAX_VECS (256) vectors in a BIO. The dm-crypt device max_segments limit, which is not set and so default to BLK_MAX_SEGMENTS (128), must thus be respected and write BIOs split accordingly. In the case of dm-flakey, since zone append emulation is not required, the block layer zone write plugging is not used and no splitting of BIOs required. Modify the function dm_zone_bio_needs_split() to use the block layer helper function bio_needs_zone_write_plugging() to force a call to bio_split_to_limits() in dm_split_and_process_bio(). This allows DM target drivers to avoid using dm_accept_partial_bio() for write operations on zoned DM devices.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2025-09-12
Last Modified
2025-11-25
Generated
2026-05-27
AI Q&A
2025-09-12
EPSS Evaluated
2026-05-25
NVD
CVE-2025-39792
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-NVD-CWE-noinfo
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves the Linux kernel's device mapper (DM) handling of write BIOs (block I/O operations) on zoned devices. Specifically, when zone append emulation is required, DM target drivers must not split BIOs using dm_accept_partial_bio() because it can cause deadlocks with queue freeze operations and invalid write sector values. The vulnerability arises from improper splitting of large BIOs, which can exceed device limits and cause errors or deadlocks. The fix ensures that large BIOs are split correctly before being processed, preventing these issues.


How can this vulnerability impact me? :

If exploited or triggered, this vulnerability can lead to deadlocks in the block I/O queue, causing system hangs or degraded performance when writing to zoned devices. It can also cause invalid write operations, potentially leading to data corruption or loss during disk writes on affected devices using the device mapper.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, ensure that your Linux kernel is updated to a version that includes the fix for this issue, which involves proper splitting of write BIOs to zoned device limits in the device mapper (dm) subsystem. Specifically, update to a kernel version that modifies dm_zone_bio_needs_split() to use bio_needs_zone_write_plugging() and enforces splitting of large BIOs before passing them to the map() function of the target. This prevents deadlocks and invalid write sector values related to zoned DM target drivers like dm-crypt and dm-flakey.


Ask Our AI Assistant
Need more information? Ask your question to get an AI reply (Powered by our expertise)
0/70
EPSS Chart