HID: nintendo: Prevent divide-by-zero on code
authorGuilherme G. Piccoli <gpiccoli@igalia.com>
Tue, 5 Dec 2023 21:15:51 +0000 (18:15 -0300)
committerJiri Kosina <jkosina@suse.com>
Mon, 18 Dec 2023 19:46:28 +0000 (20:46 +0100)
commit6eb04ca8c52e3f8c8ea7102ade81d642eee87f4a
tree1e6a1b0f76869bd9f2d556a5316dc311c571b192
parent0b7dd38c1c520b650a889a81919838671b689eb9
HID: nintendo: Prevent divide-by-zero on code

It was reported [0] that adding a generic joycon to the system caused
a kernel crash on Steam Deck, with the below panic spew:

divide error: 0000 [#1] PREEMPT SMP NOPTI
[...]
Hardware name: Valve Jupiter/Jupiter, BIOS F7A0119 10/24/2023
RIP: 0010:nintendo_hid_event+0x340/0xcc1 [hid_nintendo]
[...]
Call Trace:
 [...]
 ? exc_divide_error+0x38/0x50
 ? nintendo_hid_event+0x340/0xcc1 [hid_nintendo]
 ? asm_exc_divide_error+0x1a/0x20
 ? nintendo_hid_event+0x307/0xcc1 [hid_nintendo]
 hid_input_report+0x143/0x160
 hidp_session_run+0x1ce/0x700 [hidp]

Since it's a divide-by-0 error, by tracking the code for potential
denominator issues, we've spotted 2 places in which this could happen;
so let's guard against the possibility and log in the kernel if the
condition happens. This is specially useful since some data that
fills some denominators are read from the joycon HW in some cases,
increasing the potential for flaws.

[0] https://github.com/ValveSoftware/SteamOS/issues/1070

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Tested-by: Sam Lantinga <slouken@libsdl.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
drivers/hid/hid-nintendo.c