HID: core: Fix deadloop in hid_apply_multiplier.
authorXin Zhao <xnzhao@google.com>
Mon, 30 Jan 2023 21:29:47 +0000 (21:29 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 3 Mar 2023 10:52:22 +0000 (11:52 +0100)
commit0412fe1deab1789185e9a744c051ca262b3ee6b7
treef3f605a6ebf17da23fa0f4a5d6e41dd4f376777f
parentb7641733a4a18c6142b88098f9839fd67c37dcff
HID: core: Fix deadloop in hid_apply_multiplier.

[ Upstream commit ea427a222d8bdf2bc1a8a6da3ebe247f7dced70c ]

The initial value of hid->collection[].parent_idx if 0. When
Report descriptor doesn't contain "HID Collection", the value
remains as 0.

In the meanwhile, when the Report descriptor fullfill
all following conditions, it will trigger hid_apply_multiplier
function call.
1. Usage page is Generic Desktop Ctrls (0x01)
2. Usage is RESOLUTION_MULTIPLIER (0x48)
3. Contain any FEATURE items

The while loop in hid_apply_multiplier will search the top-most
collection by searching parent_idx == -1. Because all parent_idx
is 0. The loop will run forever.

There is a Report Descriptor triggerring the deadloop
0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
0x09, 0x48,        // Usage (0x48)
0x95, 0x01,        // Report Count (1)
0x75, 0x08,        // Report Size (8)
0xB1, 0x01,        // Feature

Signed-off-by: Xin Zhao <xnzhao@google.com>
Link: https://lore.kernel.org/r/20230130212947.1315941-1-xnzhao@google.com
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/hid/hid-core.c