Bug 2389456 (CVE-2025-38556)

Summary: CVE-2025-38556 kernel: HID: core: Harden s32ton() against conversion to 0 bits
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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OS: Linux   
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Description OSIDB Bzimport 2025-08-19 18:01:36 UTC 
In the Linux kernel, the following vulnerability has been resolved:

HID: core: Harden s32ton() against conversion to 0 bits

Testing by the syzbot fuzzer showed that the HID core gets a
shift-out-of-bounds exception when it tries to convert a 32-bit
quantity to a 0-bit quantity.  Ideally this should never occur, but
there are buggy devices and some might have a report field with size
set to zero; we shouldn't reject the report or the device just because
of that.

Instead, harden the s32ton() routine so that it returns a reasonable
result instead of crashing when it is called with the number of bits
set to 0 -- the same as what snto32() does.
Comment 1 Alexander B 2025-08-20 10:11:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025081905-CVE-2025-38556-521e@gregkh/T
Comment 3 errata-xmlrpc 2025-09-22 14:09:00 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2025:16372 https://access.redhat.com/errata/RHSA-2025:16372