Bug 2355421 (CVE-2025-21874)

Summary: CVE-2025-21874 kernel: dm-integrity: Avoid divide by zero in table status in Inline mode
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-03-27 16:02:40 UTC 
In the Linux kernel, the following vulnerability has been resolved:

dm-integrity: Avoid divide by zero in table status in Inline mode

In Inline mode, the journal is unused, and journal_sectors is zero.

Calculating the journal watermark requires dividing by journal_sectors,
which should be done only if the journal is configured.

Otherwise, a simple table query (dmsetup table) can cause OOPS.

This bug did not show on some systems, perhaps only due to
compiler optimization.

On my 32-bit testing machine, this reliably crashes with the following:

 : Oops: divide error: 0000 [#1] PREEMPT SMP
 : CPU: 0 UID: 0 PID: 2450 Comm: dmsetup Not tainted 6.14.0-rc2+ #959
 : EIP: dm_integrity_status+0x2f8/0xab0 [dm_integrity]
 ...
Comment 1 Robb Gatica 2025-03-28 02:28:54 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025032710-CVE-2025-21874-d5d9@gregkh/T