From: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com> stable inclusion from stable-6.6.102 commit 9b2a3e7189028aa7c4d53a84364f2ea9fb209787 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICUC98 CVE: CVE-2025-38632 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 0b075c011032f88d1cfde3b45d6dcf08b44140eb ] commit 5a3e85c3c397 ("pinmux: Use sequential access to access desc->pinmux data") tried to address the issue when two client of the same gpio calls pinctrl_select_state() for the same functionality, was resulting in NULL pointer issue while accessing desc->mux_owner. However, issue was not completely fixed due to the way it was handled and it can still result in the same NULL pointer. The issue occurs due to the following interleaving: cpu0 (process A) cpu1 (process B) pin_request() { pin_free() { mutex_lock() desc->mux_usecount--; //becomes 0 .. mutex_unlock() mutex_lock(desc->mux) desc->mux_usecount++; // becomes 1 desc->mux_owner = owner; mutex_unlock(desc->mux) mutex_lock(desc->mux) desc->mux_owner = NULL; mutex_unlock(desc->mux) This sequence leads to a state where the pin appears to be in use (`mux_usecount == 1`) but has no owner (`mux_owner == NULL`), which can cause NULL pointer on next pin_request on the same pin. Ensure that updates to mux_usecount and mux_owner are performed atomically under the same lock. Only clear mux_owner when mux_usecount reaches zero and no new owner has been assigned. Fixes: 5a3e85c3c397 ("pinmux: Use sequential access to access desc->pinmux data") Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com> Link: https://lore.kernel.org/20250708-pinmux-race-fix-v2-1-8ae9e8a0d1a1@oss.qualc... Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: drivers/pinctrl/pinmux.c [wxf: fix conflicts because 'scoped_guard' is not introduced.] Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- drivers/pinctrl/pinmux.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c index 53fe25e9e8647..92cd855f37487 100644 --- a/drivers/pinctrl/pinmux.c +++ b/drivers/pinctrl/pinmux.c @@ -247,18 +247,7 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, return NULL; } } - mutex_unlock(&desc->mux_lock); - - /* - * If there is no kind of request function for the pin we just assume - * we got it by default and proceed. - */ - if (gpio_range && ops->gpio_disable_free) - ops->gpio_disable_free(pctldev, gpio_range, pin); - else if (ops->free) - ops->free(pctldev, pin); - mutex_lock(&desc->mux_lock); if (gpio_range) { owner = desc->gpio_owner; desc->gpio_owner = NULL; @@ -269,6 +258,15 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin, } mutex_unlock(&desc->mux_lock); + /* + * If there is no kind of request function for the pin we just assume + * we got it by default and proceed. + */ + if (gpio_range && ops->gpio_disable_free) + ops->gpio_disable_free(pctldev, gpio_range, pin); + else if (ops->free) + ops->free(pctldev, pin); + module_put(pctldev->owner); return owner; -- 2.20.1