4.9-stable review patch. If anyone has any objections, please let me know.
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From: Timur Tabi timur@codeaurora.org
commit ab3dbcf78f60f46d6a0ad63b1f4b690b7a427140 upstream.
If the main loop in linehandle_create() encounters an error, it unwinds completely by freeing all previously requested GPIO descriptors. However, if the error occurs in the beginning of the loop before that GPIO is requested, then the exit code attempts to free a null descriptor. If extrachecks is enabled, gpiod_free() triggers a WARN_ON.
Instead, keep a separate count of legitimate GPIOs so that only those are freed.
Cc: stable@vger.kernel.org Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines") Reviewed-by: Bjorn Andersson bjorn.andersson@linaro.org Signed-off-by: Timur Tabi timur@codeaurora.org Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpio/gpiolib.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -425,7 +425,7 @@ static int linehandle_create(struct gpio struct gpiohandle_request handlereq; struct linehandle_state *lh; struct file *file; - int fd, i, ret; + int fd, i, count = 0, ret;
if (copy_from_user(&handlereq, ip, sizeof(handlereq))) return -EFAULT; @@ -471,6 +471,7 @@ static int linehandle_create(struct gpio if (ret) goto out_free_descs; lh->descs[i] = desc; + count = i;
if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW) set_bit(FLAG_ACTIVE_LOW, &desc->flags); @@ -537,7 +538,7 @@ static int linehandle_create(struct gpio out_put_unused_fd: put_unused_fd(fd); out_free_descs: - for (; i >= 0; i--) + for (i = 0; i < count; i++) gpiod_free(lh->descs[i]); kfree(lh->label); out_free_lh: