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CVE-2026-64364

HID: multitouch: fix out-of-bounds bit access on mt_io_flags

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 3 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: HID: multitouch: fix out-of-bounds bit access on mt_io_flags mt_io_flags is a single unsigned long, but mt_process_slot(), mt_release_pending_palms() and mt_release_contacts() use it as a per-slot bitmap indexed by the slot number. That slot number is only bounded by td->maxcontacts, which is taken from the device's ContactCountMaximum feature report and can be up to 255, not by BITS_PER_LONG. As a result, a multitouch device that advertises a large contact count makes set_bit()/clear_bit() operate past the mt_io_flags word and corrupt the adjacent members of struct mt_device. The sticky-fingers release timer is the easiest way to reach this. mt_release_contacts() runs for (i = 0; i < mt->num_slots; i++) clear_bit(i, &td->mt_io_flags); with num_slots == maxcontacts. For maxcontacts around 250 the loop clears the bits that overlap td->applications.next, zeroing that list head, and the list_for_each_entry() that immediately follows then dereferences NULL. The kernel panics from timer (softirq) context. On a KASAN build this shows up as a general protection fault in mt_release_contacts() with a null-ptr-deref at offset 0x58, which is offsetof(struct mt_application, num_received). The state is reachable from an untrusted USB or Bluetooth HID multitouch device; no local privileges are required. Store the per-slot active state in a separately allocated bitmap sized for maxcontacts, the same pattern already used for pending_palm_slots, and keep only MT_IO_FLAGS_RUNNING in mt_io_flags. The two "mt_io_flags & MT_IO_SLOTS_MASK" arming checks become bitmap_empty(td->active_slots, td->maxcontacts). Move MT_IO_FLAGS_RUNNING back to bit 0. It was bumped to bit 32 by the same commit to leave the low byte for the slot bits; with the slot bits gone it fits in bit 0 again, which also keeps it within the unsigned long on 32-bit.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From fc488f675344931ffab6a51c43691065ec006567 · fixed in 12e90656e330ff8bbaf2f29c535fdb8a11cc6f55; From 77711d850bed75ae7142c3d1f22c1a8b4d049c33 · fixed in 152983d87387f6a8ae72b73474cfa55fbcf1ec75; From 6acfe25968913788d30ec0eedd80178c4ea3f1d0 · fixed in b5c037d6b807017e74a115288f81bc9cd5a5aab8; From d280c138e66be87d1fccfed42593f02fdb893905 · fixed in a6d5ce2e1a2d7bf189bde8a659d04b65f0b0725d; From f32fea4c0234c971c12e46d76612cdc2dd4bb046 · fixed in e24918ee67c4dc3d20d4670750e46e9b160365f4; From 46f781e0d151844589dc2125c8cce3300546f92a · fixed in 37daa8c96bd563d03150e23f094cb60703594a6d; From 46f781e0d151844589dc2125c8cce3300546f92a · fixed in 6493ebf9489efef0105078377b973ab33d51af22; From 46f781e0d151844589dc2125c8cce3300546f92a · fixed in 8813b0612275cc61fe9e6603d0ee019247ade6be; From 5.10.246 · fixed in 5.10.261; From 5.15.196 · fixed in 5.15.212; From 6.1.158 · fixed in 6.1.178; From 6.6.114 · fixed in 6.6.145; From 6.12.55 · fixed in 6.12.97; From 6.17.5 · fixed in 6.18

  • Linux Linux

    6.18

  • KernelLinux

    fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.39; From 6.18.0 · fixed in 7.1.4

References 8

git.kernel.org