CVE-2026-64427

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> HID: logitech-dj: Fix maxfield check in DJ short report validation<br /> <br /> Commit b6a57912854e ("HID: logitech-dj: Prevent REPORT_ID_DJ_SHORT<br /> related user initiated OOB write") added validation for the DJ short<br /> output report, but the error path dereferences rep-&gt;field[0] even when<br /> rep-&gt;maxfield is zero.<br /> <br /> Commit 8b9a097eb2fc ("HID: logitech-dj: fix wrong detection of bad<br /> DJ_SHORT output report") made the check conditional on rep being present,<br /> but a crafted descriptor can still create report ID 0x20 with only padding<br /> output items. hid-core registers the report, ignores the padding field,<br /> and leaves rep-&gt;maxfield as zero.<br /> <br /> In that case the validation enters the rep-&gt;maxfield field[0]-&gt;report_count while printing the error message,<br /> causing a NULL pointer dereference during probe. This is reproducible with<br /> uhid by emulating a Logitech receiver with a padding-only DJ short output<br /> report:<br /> <br /> BUG: KASAN: null-ptr-deref in logi_dj_probe+0xb1/0x754 [hid_logitech_dj]<br /> Read of size 4 at addr 0000000000000028 by task kworker/4:1/129<br /> ...<br /> Call Trace:<br /> logi_dj_probe+0xb1/0x754 [hid_logitech_dj]<br /> hid_device_probe+0x329/0x3f0 [hid]<br /> really_probe+0x162/0x570<br /> __device_attach+0x137/0x2c0<br /> bus_probe_device+0x38/0xc0<br /> device_add+0xa56/0xce0<br /> hid_add_device+0x19c/0x280 [hid]<br /> uhid_device_add_worker+0x2c/0xb0 [uhid]<br /> <br /> Reject the zero-field report before printing the field report_count.