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Mukesh Ojha
2da32aed4a
[ Upstream commit 5a3e85c3c3 ]
When two client of the same gpio call pinctrl_select_state() for the
same functionality, we are seeing NULL pointer issue while accessing
desc->mux_owner.
Let's say two processes A, B executing in pin_request() for the same pin
and process A updates the desc->mux_usecount but not yet updated the
desc->mux_owner while process B see the desc->mux_usecount which got
updated by A path and further executes strcmp and while accessing
desc->mux_owner it crashes with NULL pointer.
Serialize the access to mux related setting with a mutex lock.
cpu0 (process A) cpu1(process B)
pinctrl_select_state() { pinctrl_select_state() {
pin_request() { pin_request() {
...
....
} else {
desc->mux_usecount++;
desc->mux_usecount && strcmp(desc->mux_owner, owner)) {
if (desc->mux_usecount > 1)
return 0;
desc->mux_owner = owner;
} }
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Link: https://lore.kernel.org/20241014192930.1539673-1-quic_mojha@quicinc.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
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