CVE-2026-80918: HID: core: fix number/pointer type confusion on long items

CVE-2026-80918: HID: core: fix number/pointer type confusion on long items

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

HID: core: fix number/pointer type confusion on long items

When fetch_item() is called by hid_scan_report() on an item with
HID_ITEM_TAG_LONG, it stores a pointer to the item data in
item->data.longdata instead of storing a value directly in
item->data.{u8/u16/u32}.

When item_udata() or item_sdata() encounters such an item, it incorrectly
assumes that the item is in short format, and therefore returns the lower
part of a kernel pointer reinterpreted as a number.

When a HID device is connected whose descriptor contains a
HID_GLOBAL_ITEM_TAG_REPORT_SIZE encoded in long format with size=4, this
causes the lower half of a kernel pointer to be printed into dmesg as a
number, like this:

    hid (null): invalid report_size 107953555

To fix it, let item_udata() and item_sdata() verify that the item is in
short format.

Note that this bug only affects hid_scan_report(), while the main parsing
pass hid_parse_collections() will always bail out when encountering a long
item.

Sidenote: There are currently no users of data.longdata; maybe we should
just remove any parsing of long-format descriptors as a follow-up.

The Linux kernel CVE team has assigned CVE-2026-80918 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 5.10.267 with commit bed7fe3a936b6bdd84671385951397ca673cf6e7
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 5.15.218 with commit aec2c2ec87d4ec1f098979f68cd81b29f031c8cb
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 6.1.185 with commit 634f498ea5d5e8e01f8d9414d4f45eeaf9ee1996
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 6.6.154 with commit abec577de5fc16cd5caae42f97cdcd0983c06d66
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 6.12.106 with commit dd8035dec26e98204d6e4a6e0cee5c4d329b3d7e
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 6.18.47 with commit 1fa1591efd417e39e5e164bebea8ca7a3837c469
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 7.1.11 with commit e60159f5ea60254a5c3de4ea4f2f939f0171031b
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 7.2.1 with commit e542edada3f79387c0ac2a528cebf01f4ef47df8
	Issue introduced in 3.12 with commit 3dc8fc083dbfeede7b63a0c07581192e97711365 and fixed in 7.3-rc1 with commit 28abce951343fcec26e397610868efa4e1395c3f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80918
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/hid/hid-core.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/bed7fe3a936b6bdd84671385951397ca673cf6e7
	https://git.kernel.org/stable/c/aec2c2ec87d4ec1f098979f68cd81b29f031c8cb
	https://git.kernel.org/stable/c/634f498ea5d5e8e01f8d9414d4f45eeaf9ee1996
	https://git.kernel.org/stable/c/abec577de5fc16cd5caae42f97cdcd0983c06d66
	https://git.kernel.org/stable/c/dd8035dec26e98204d6e4a6e0cee5c4d329b3d7e
	https://git.kernel.org/stable/c/1fa1591efd417e39e5e164bebea8ca7a3837c469
	https://git.kernel.org/stable/c/e60159f5ea60254a5c3de4ea4f2f939f0171031b
	https://git.kernel.org/stable/c/e542edada3f79387c0ac2a528cebf01f4ef47df8
	https://git.kernel.org/stable/c/28abce951343fcec26e397610868efa4e1395c3f