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authorWill Deacon <will@kernel.org>2019-10-02 15:42:06 +0300
committerLinus Walleij <linus.walleij@linaro.org>2019-10-03 15:50:16 +0300
commitbe4c60b563edee3712d392aaeb0943a768df7023 (patch)
treeac614e11eb968b58841fe4c887d13f2d5fe5fba7 /drivers/pinctrl/devicetree.c
parent09107a51b096fbac3ea32d9ea150ddf029cbc358 (diff)
downloadlinux-be4c60b563edee3712d392aaeb0943a768df7023.tar.xz
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: Elena Petrova <lenaptr@google.com> Tested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20191002124206.22928-1-will@kernel.org Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/pinctrl/devicetree.c')
-rw-r--r--drivers/pinctrl/devicetree.c25
1 files changed, 20 insertions, 5 deletions
diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index 5d6d8b1e9062..dbaacde1b36a 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -29,6 +29,13 @@ 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)
@@ -63,7 +70,13 @@ 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);
@@ -71,10 +84,8 @@ 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;
@@ -82,6 +93,10 @@ 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)