Bug 2461477 (CVE-2026-31624) - CVE-2026-31624 kernel: HID: core: clamp report_size in s32ton() to avoid undefined shift
Summary: CVE-2026-31624 kernel: HID: core: clamp report_size in s32ton() to avoid unde...
Keywords:
Status: NEW
Alias: CVE-2026-31624
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-24 15:03 UTC by OSIDB Bzimport
Modified: 2026-04-24 20:28 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-04-24 15:03:46 UTC
In the Linux kernel, the following vulnerability has been resolved:

HID: core: clamp report_size in s32ton() to avoid undefined shift

s32ton() shifts by n-1 where n is the field's report_size, a value that
comes directly from a HID device.  The HID parser bounds report_size
only to <= 256, so a broken HID device can supply a report descriptor
with a wide field that triggers shift exponents up to 256 on a 32-bit
type when an output report is built via hid_output_field() or
hid_set_field().

Commit ec61b41918587 ("HID: core: fix shift-out-of-bounds in
hid_report_raw_event") added the same n > 32 clamp to the function
snto32(), but s32ton() was never given the same fix as I guess syzbot
hadn't figured out how to fuzz a device the same way.

Fix this up by just clamping the max value of n, just like snto32()
does.


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