Bug 2516601 (CVE-2026-72104)

Summary: CVE-2026-72104 kernel: dm-pcache: reject option groups without values
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's device-mapper pcache target. A local user could trigger a system crash by providing a malformed table to the pcache target. This occurs because the system attempts to process an option without a value, leading to a critical error. The primary impact is a Denial of Service (DoS), which could make the system unavailable.
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Description OSIDB Bzimport 2026-08-15 06:21:15 UTC 
In the Linux kernel, the following vulnerability has been resolved:

dm-pcache: reject option groups without values

The pcache target parses optional arguments as name/value pairs.  A
table that advertises one optional argument and supplies only a
recognized option name, for example "cache_mode", reaches
parse_cache_opts() with argc == 1.  The parser consumes the name,
decrements argc to zero, then calls dm_shift_arg() again for the value.
dm_shift_arg() returns NULL when no arguments remain, and the following
strcmp() dereferences that NULL pointer.

Check that each recognized option has a value before consuming it.  This
keeps valid "cache_mode writeback" and "data_crc true/false" tables
unchanged while making malformed tables fail during target construction
with a precise missing-value error.
Comment 1 Keith Grant 2026-08-17 21:52:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081525-CVE-2026-72104-35cf@gregkh/T