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Commit 4c2eddf7 authored by Will Deacon's avatar Will Deacon Committed by Elena Petrova
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FROMGIT: pinctrl: devicetree: Avoid taking direct reference to device name string 



When populating the pinctrl mapping table entries for a device, the
'dev_name' field for each entry is initialised to point directly at the
string returned by 'dev_name()' for the device and subsequently used by
'create_pinctrl()' when looking up the mappings for the device being
probed.

This is unreliable in the presence of calls to 'dev_set_name()', which may
reallocate the device name string leaving the pinctrl mappings with a
dangling reference. This then leads to a use-after-free every time the
name is dereferenced by a device probe:

  | BUG: KASAN: invalid-access in strcmp+0x20/0x64
  | Read of size 1 at addr 13ffffc153494b00 by task modprobe/590
  | Pointer tag: [13], memory tag: [fe]
  |
  | Call trace:
  |  __kasan_report+0x16c/0x1dc
  |  kasan_report+0x10/0x18
  |  check_memory_region
  |  __hwasan_load1_noabort+0x4c/0x54
  |  strcmp+0x20/0x64
  |  create_pinctrl+0x18c/0x7f4
  |  pinctrl_get+0x90/0x114
  |  devm_pinctrl_get+0x44/0x98
  |  pinctrl_bind_pins+0x5c/0x450
  |  really_probe+0x1c8/0x9a4
  |  driver_probe_device+0x120/0x1d8

Follow the example of sysfs, and duplicate the device name string before
stashing it away in the pinctrl mapping entries.

Cc: Linus Walleij <linus.walleij@linaro.org>
Reported-by: default avatarElena Petrova <lenaptr@google.com>
Tested-by: default avatarElena Petrova <lenaptr@google.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20191002124206.22928-1-will@kernel.org


Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>

(cherry picked from commit be4c60b563edee3712d392aaeb0943a768df7023
https: //git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git
devel)
Bug: 140550171
Signed-off-by: default avatarElena Petrova <lenaptr@google.com>
Change-Id: Ia54c7088590ab0f9adc7753c191bba85c06dfdc1
parent 22ab89bf

drivers/pinctrl/devicetree.c

+20 −5
Original line number Diff line number Diff line
@@ -40,6 +40,13 @@ struct pinctrl_dt_map { 
static void dt_free_map(struct pinctrl_dev *pctldev,

		     struct pinctrl_map *map, unsigned num_maps)

{

	int i;



	for (i = 0; i < num_maps; ++i) {

		kfree_const(map[i].dev_name);

		map[i].dev_name = NULL;

	}



	if (pctldev) {

		const struct pinctrl_ops *ops = pctldev->desc->pctlops;

		if (ops->dt_free_map)
@@ -74,7 +81,13 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, 


	/* Initialize common mapping table entry fields */

	for (i = 0; i < num_maps; i++) {

		map[i].dev_name = dev_name(p->dev);

		const char *devname;



		devname = kstrdup_const(dev_name(p->dev), GFP_KERNEL);

		if (!devname)

			goto err_free_map;



		map[i].dev_name = devname;

		map[i].name = statename;

		if (pctldev)

			map[i].ctrl_dev_name = dev_name(pctldev->dev);
@@ -82,10 +95,8 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, 


	/* Remember the converted mapping table entries */

	dt_map = kzalloc(sizeof(*dt_map), GFP_KERNEL);

	if (!dt_map) {

		dt_free_map(pctldev, map, num_maps);

		return -ENOMEM;

	}

	if (!dt_map)

		goto err_free_map;



	dt_map->pctldev = pctldev;

	dt_map->map = map;
@@ -93,6 +104,10 @@ static int dt_remember_or_free_map(struct pinctrl *p, const char *statename, 
	list_add_tail(&dt_map->node, &p->dt_maps);



	return pinctrl_register_map(map, num_maps, false);



err_free_map:

	dt_free_map(pctldev, map, num_maps);

	return -ENOMEM;

}



struct pinctrl_dev *of_pinctrl_get(struct device_node *np)