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gpiolib: Fix potential NULL pointer dereference in gpiod_get_label()

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In `gpiod_get_label()`, it is possible that `srcu_dereference_check()` may
return a NULL pointer, leading to a scenario where `label->str` is accessed
without verifying if `label` itself is NULL.

This patch adds a proper NULL check for `label` before accessing
`label->str`. The check for `label->str != NULL` is removed because
`label->str` can never be NULL if `label` is not NULL.

This fixes the issue where the label name was being printed as `(efault)`
when dumping the sysfs GPIO file when `label == NULL`.

Fixes: 5a646e03e9 ("gpiolib: Return label, if set, for IRQ only line")
Fixes: a86d276930 ("gpiolib: fix the speed of descriptor label setting with SRCU")
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20241003131351.472015-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Lad Prabhakar 2024-10-03 14:13:51 +01:00 committed by Bartosz Golaszewski
parent 5a431e50e9
commit 7b99b5ab88
1 changed files with 2 additions and 2 deletions
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4
drivers/gpio/gpiolib.c
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@ -114,12 +114,12 @@ const char *gpiod_get_label(struct gpio_desc *desc)
srcu_read_lock_held(&desc->gdev->desc_srcu)); srcu_read_lock_held(&desc->gdev->desc_srcu));
if (test_bit(FLAG_USED_AS_IRQ, &flags)) if (test_bit(FLAG_USED_AS_IRQ, &flags))
return label->str ?: "interrupt"; return label ? label->str : "interrupt";
if (!test_bit(FLAG_REQUESTED, &flags)) if (!test_bit(FLAG_REQUESTED, &flags))
return NULL; return NULL;
return label->str; return label ? label->str : NULL;
} }
static void desc_free_label(struct rcu_head *rh) static void desc_free_label(struct rcu_head *rh)