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gpiolib: don't report -ENOMEM for a requested line without a label

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gpiod_request_commit() sets GPIOD_FLAG_REQUESTED, calls ->request() and
only then sets the label. A line in between has no label, so
gpiochip_dup_line_label() passes NULL to kstrdup() and returns
ERR_PTR(-ENOMEM), which for_each_hwgpio() then passes to kfree():

  BUG: unable to handle page fault for address: ffcc73074355ffc8
  Call Trace:
   gpio_sim_dbg_show
   gpiolib_seq_show
   seq_read_iter

Return NULL for such a line, as for an unrequested one.

Reproduced with gpio-sim: reading /sys/kernel/debug/gpio in a loop while
lines are requested and released oopses within seconds; with this
change, 100000 cycles pass.

Fixes: 35b545332b ("gpio: remove gpio_lock")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20261020-gpiolib-chip-removal-v3-0-aambrozewicz@nvidia.com?part=2
Assisted-by: LLM
Signed-off-by: Adrian Ambrozewicz <aambrozewicz@nvidia.com>
Link: https://patch.msgid.link/20261022083343.3905973-3-aambrozewicz@nvidia.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This commit is contained in:
Adrian Ambrozewicz 2026-10-22 11:33:44 +03:00 committed by Bartosz Golaszewski
parent 1566504702
commit dae7391374
1 changed files with 6 additions and 1 deletions
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7
drivers/gpio/gpiolib.c
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@ -2721,6 +2721,7 @@ void gpiod_free(struct gpio_desc *desc)
char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_desc *desc;
const char *name;
char *label;
desc = gpiochip_get_desc(gc, offset);
@ -2732,7 +2733,11 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
guard(srcu)(&desc->gdev->desc_srcu);
label = kstrdup(gpiod_get_label(desc), GFP_KERNEL);
name = gpiod_get_label(desc);
if (!name)
return NULL;
label = kstrdup(name, GFP_KERNEL);
if (!label)
return ERR_PTR(-ENOMEM);