[PATCH v4] gpio: sim: fix an invalid __free() usage

Bartosz Golaszewski
2023-09-18T16:26:24Z

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

gpio_sim_make_line_names() returns NULL or ERR_PTR() so we must not use
__free(kfree) on the returned address. Split this function into two, one
that determines the size of the "gpio-line-names" array to allocate and
one that actually sets the names at correct offsets. The allocation and
assignment of the managed pointer happens in between.

Fixes: 3faf89f27aab ("gpio: sim: simplify code with cleanup helpers")
Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Closes: https://lore.kernel.org/all/07c32bf1-6c1a-49d9-b97d-f0ae4a2b42ab@p183/
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Linus,

I followed the pattern for determining the size of the line-names array
from your patch in the end but with a changed variable naming. If this is
fine, I'll queue it for fixes for the next rc.

Bart

v3 -> v4:
- simplify the line counting logic

v2 -> v3:
- restore the offset out-of-bounds checks

v1 -> v2:
- split the line name setting into two parts

drivers/gpio/gpio-sim.c | 59 +++++++++++++++--------------------------
1 file changed, 22 insertions(+), 37 deletions(-)

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 460389bb8e3f..b66abb55ef4d 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -718,52 +718,32 @@ gpio_sim_device_config_live_show(struct config_item *item, char *page)
return sprintf(page, "%c\n", live ? '1' : '0');
}

-static char **gpio_sim_make_line_names(struct gpio_sim_bank *bank,
- unsigned int *line_names_size)
+static unsigned int gpio_sim_get_line_names_size(struct gpio_sim_bank *bank)
{
- unsigned int max_offset = 0;
- bool has_line_names = false;
struct gpio_sim_line *line;
- char **line_names;
+ unsigned int size = 0;

list_for_each_entry(line, &bank->line_list, siblings) {
- if (line->offset >= bank->num_lines)
+ if (!line->name || (line->offset >= bank->num_lines))
continue;

- if (line->name) {
- if (line->offset > max_offset)
- max_offset = line->offset;
-
- /*
- * max_offset can stay at 0 so it's not an indicator
- * of whether line names were configured at all.
- */
- has_line_names = true;
- }
+ size = line->offset + 1;
}

- if (!has_line_names)
- /*
- * This is not an error - NULL means, there are no line
- * names configured.
- */
- return NULL;
-
- *line_names_size = max_offset + 1;
+ return size;
+}

- line_names = kcalloc(*line_names_size, sizeof(*line_names), GFP_KERNEL);
- if (!line_names)
- return ERR_PTR(-ENOMEM);
+static void
+gpio_sim_set_line_names(struct gpio_sim_bank *bank, char **line_names)
+{
+ struct gpio_sim_line *line;

list_for_each_entry(line, &bank->line_list, siblings) {
- if (line->offset >= bank->num_lines)
+ if (!line->name || (line->offset >= bank->num_lines))
continue;

- if (line->name && (line->offset <= max_offset))
- line_names[line->offset] = line->name;
+ line_names[line->offset] = line->name;
}
-
- return line_names;
}

static void gpio_sim_remove_hogs(struct gpio_sim_device *dev)
@@ -867,7 +847,7 @@ gpio_sim_make_bank_swnode(struct gpio_sim_bank *bank,
struct fwnode_handle *parent)
{
struct property_entry properties[GPIO_SIM_PROP_MAX];
- unsigned int prop_idx = 0, line_names_size = 0;
+ unsigned int prop_idx = 0, line_names_size;
char **line_names __free(kfree) = NULL;

memset(properties, 0, sizeof(properties));
@@ -878,14 +858,19 @@ gpio_sim_make_bank_swnode(struct gpio_sim_bank *bank,
properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
bank->label);

- line_names = gpio_sim_make_line_names(bank, &line_names_size);
- if (IS_ERR(line_names))
- return ERR_CAST(line_names);
+ line_names_size = gpio_sim_get_line_names_size(bank);
+ if (line_names_size) {
+ line_names = kcalloc(line_names_size, sizeof(*line_names),
+ GFP_KERNEL);
+ if (!line_names)
+ return ERR_PTR(-ENOMEM);
+
+ gpio_sim_set_line_names(bank, line_names);

- if (line_names)
properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
"gpio-line-names",
line_names, line_names_size);
+ }

return fwnode_create_software_node(properties, parent);
}
--
2.39.2