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This may leak the kernel stack contents. Make gpio_desc_to_lineinfo() return int so that the -ENODEV returned on failure to acquire the guard can be propagated to the callers. While not strictly necessary: move the memset() before trying to acquire the SRCU read lock too for good measure. Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260912123529.7951-1-tzungbi%40kernel.org?part=3 Signed-off-by: Bartosz Golaszewski --- Changes in v2: - Make gpio_desc_to_lineinfo() return an integer return value so that the error code returned in case of a failure to acquire the guard can be propagated down the stack - Link to v1: https://patch.msgid.link/20260917-gpio-cdev-stack-leak-fixes-v1-1-2bb52879e49c@oss.qualcomm.com --- drivers/gpio/gpiolib-cdev.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index b5da6e8566dcd777ef4e7784989b722416c07fd3..f8ef7367b8c856986237dcc3a425a7152fc2db20 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -2174,18 +2174,19 @@ static void gpio_v2_line_info_changed_to_v1( #endif /* CONFIG_GPIO_CDEV_V1 */ -static void gpio_desc_to_lineinfo(struct gpio_desc *desc, - struct gpio_v2_line_info *info, bool atomic) +static int gpio_desc_to_lineinfo(struct gpio_desc *desc, + struct gpio_v2_line_info *info, bool atomic) { u32 debounce_period_us; unsigned long dflags; const char *label; + memset(info, 0, sizeof(*info)); + CLASS(gpio_chip_guard, guard)(desc); if (!guard.gc) - return; + return -ENODEV; - memset(info, 0, sizeof(*info)); info->offset = gpiod_hwgpio(desc); if (desc->name) @@ -2260,6 +2261,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, debounce_period_us; info->num_attrs++; } + + return 0; } struct gpio_chardev_data { @@ -2311,6 +2314,7 @@ static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip, struct gpio_desc *desc; struct gpioline_info lineinfo; struct gpio_v2_line_info lineinfo_v2; + int ret; if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) return -EFAULT; @@ -2328,7 +2332,10 @@ static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip, return -EBUSY; } - gpio_desc_to_lineinfo(desc, &lineinfo_v2, false); + ret = gpio_desc_to_lineinfo(desc, &lineinfo_v2, false); + if (ret) + return ret; + gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo); if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) { @@ -2346,6 +2353,7 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip, { struct gpio_desc *desc; struct gpio_v2_line_info lineinfo; + int ret; if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) return -EFAULT; @@ -2365,7 +2373,10 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip, if (test_and_set_bit(lineinfo.offset, cdev->watched_lines)) return -EBUSY; } - gpio_desc_to_lineinfo(desc, &lineinfo, false); + + ret = gpio_desc_to_lineinfo(desc, &lineinfo, false); + if (ret) + return ret; if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) { if (watch) @@ -2491,6 +2502,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb, struct lineinfo_changed_ctx *ctx; struct gpio_desc *desc = data; struct file *fp; + int ret; if (!test_bit(gpiod_hwgpio(desc), cdev->watched_lines)) return NOTIFY_DONE; @@ -2521,7 +2533,14 @@ static int lineinfo_changed_notify(struct notifier_block *nb, ctx->chg.event_type = action; ctx->chg.timestamp_ns = ktime_get_ns(); - gpio_desc_to_lineinfo(desc, &ctx->chg.info, true); + + ret = gpio_desc_to_lineinfo(desc, &ctx->chg.info, true); + if (ret) { + fput(fp); + pr_err("GPIO controller that generated the line info notification was removed\n"); + return NOTIFY_DONE; + } + /* Keep the GPIO device alive until we emit the event. */ ctx->gdev = gpio_device_get(desc->gdev); ctx->cdev = cdev; --- base-commit: 0d9d0dbf2fddcff5859d623e90ca73c4054276e1 change-id: 20260917-gpio-cdev-stack-leak-fixes-84ad8918a6e0 Best regards, -- Bartosz Golaszewski