Affected: Alpaquita:23: linux-lts, Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

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

HID: picolcd: clamp eeprom debugfs read to bytes actually received

picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte supplied by the device in its REPORT_EE_DATA reply -- clamped only to the caller's read() count:

ret = resp->raw_data[2]; if (ret > s) ret = s; if (copy_to_user(u, resp->raw_data+3, ret))

It never checks resp->raw_size, the number of bytes picolcd_raw_event() actually copied into the 64-byte raw_data[] of the kmalloc'd struct picolcd_pending. A device (or a spoofed picoLCD) returning a length byte of 0xff, read with a count >= 255, makes copy_to_user() read past raw_data[] into adjacent slab memory and return it to userspace through the debugfs "eeprom" file:

BUG: KASAN: slab-out-of-bounds in _copy_to_user Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd]

The debug-dump path in the same file already validates the device length byte against the received size before trusting it; this read does not. The file is created S_IRUSR (root-only) and a crafted device is needed, so it is neither unprivileged- nor remotely-triggerable.

Clamp the copy length to resp->raw_size - 3 (the payload actually received, minus the 3-byte header), floored at 0 for short replies.

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

HID: picolcd: clamp eeprom debugfs read to bytes actually received

picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte supplied by the device in its REPORT_EE_DATA reply -- clamped only to the caller's read() count:

ret = resp->raw_data[2]; if (ret > s) ret = s; if (copy_to_user(u, resp->raw_data+3, ret))

It never checks resp->raw_size, the number of bytes picolcd_raw_event() actually copied into the 64-byte raw_data[] of the kmalloc'd struct picolcd_pending. A device (or a spoofed picoLCD) returning a length byte of 0xff, read with a count >= 255, makes copy_to_user() read past raw_data[] into adjacent slab memory and return it to userspace through the debugfs "eeprom" file:

BUG: KASAN: slab-out-of-bounds in _copy_to_user Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd]

The debug-dump path in the same file already validates the device length byte against the received size before trusting it; this read does not. The file is created S_IRUSR (root-only) and a crafted device is needed, so it is neither unprivileged- nor remotely-triggerable.

Clamp the copy length to resp->raw_size - 3 (the payload actually received, minus the 3-byte header), floored at 0 for short replies.

kernel-devel-7.2.7-1.1 on GA media

Affected: Ubuntu:Pro:14.04:LTS: linux, Ubuntu:Pro:14.04:LTS: linux-aws, Ubuntu:Pro:14.04:LTS: linux-azure, Ubuntu:Pro:14.04:LTS: linux-lts-xenial, Ubuntu:Pro:16.04:LTS: linux, Ubuntu:Pro:16.04:LTS: linux-aws, Ubuntu:Pro:16.04:LTS: linux-aws-hwe, Ubuntu:Pro:16.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-gcp, Ubuntu:Pro:16.04:LTS: linux-hwe and 246 more

In the Linux kernel, the following vulnerability has been resolved: HID: picolcd: clamp eeprom debugfs read to bytes actually received picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte supplied by the device in its REPORT_EE_DATA reply -- clamped only to the caller's read() count: ret = resp->raw_data[2]; if (ret > s) ret = s; if (copy_to_user(u, resp->raw_data+3, ret)) It never checks resp->raw_size, the number of bytes picolcd_raw_event() actually copied into the 64-byte raw_data[] of the kmalloc'd struct picolcd_pending. A device (or a spoofed picoLCD) returning a length byte of 0xff, read with a count >= 255, makes copy_to_user() read past raw_data[] into adjacent slab memory and return it to userspace through the debugfs "eeprom" file: BUG: KASAN: slab-out-of-bounds in _copy_to_user Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd] The debug-dump path in the same file already validates the device length byte against the received size before trusting it; this read does not. The file is created S_IRUSR (root-only) and a crafted device is needed, so it is neither unprivileged- nor remotely-triggerable. Clamp the copy length to resp->raw_size - 3 (the payload actually received, minus the 3-byte header), floored at 0 for short replies.