Commits
Roderick Colenbrander committed e0f6974a54d
HID: sony: Fix race condition between rumble and device remove. Valve reported a kernel crash on Ubuntu 18.04 when disconnecting a DS4 gamepad while rumble is enabled. This issue is reproducible with a frequency of 1 in 3 times in the game Borderlands 2 when using an automatic weapon, which triggers many rumble operations. We found the issue to be a race condition between sony_remove and the final device destruction by the HID / input system. The problem was that sony_remove didn't clean some of its work_item state in "struct sony_sc". After sony_remove work, the corresponding evdev node was around for sufficient time for applications to still queue rumble work after "sony_remove". On pre-4.19 kernels the race condition caused a kernel crash due to a NULL-pointer dereference as "sc->output_report_dmabuf" got freed during sony_remove. On newer kernels this crash doesn't happen due the buffer now being allocated using devm_kzalloc. However we can still queue work, while the driver is an undefined state. This patch fixes the described problem, by guarding the work_item "state_worker" with an initialized variable, which we are setting back to 0 on cleanup. Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com> CC: stable@vger.kernel.org Signed-off-by: Jiri Kosina <jkosina@suse.cz>