lkml.org 
[lkml]   [2018]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.16 24/72] gpioib: do not free unrequested descriptors
Date
4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

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
@@ -446,7 +446,7 @@ 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;
u32 lflags;

if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
@@ -507,6 +507,7 @@ 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);
@@ -577,7 +578,7 @@ 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:

\
 
 \ /
  Last update: 2018-05-14 09:10    [W:0.256 / U:0.252 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site