From: Will Deacon will@kernel.org
commit be4c60b563edee3712d392aaeb0943a768df7023 upstream.
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 [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pinctrl/devicetree.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c index fe04e748dfe4b..eb8c29f3e16ef 100644 --- a/drivers/pinctrl/devicetree.c +++ b/drivers/pinctrl/devicetree.c @@ -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; ops->dt_free_map(pctldev, map, num_maps); @@ -73,7 +80,13 @@ 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); @@ -81,11 +94,8 @@ 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) { - dev_err(p->dev, "failed to alloc struct pinctrl_dt_map\n"); - 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 +103,10 @@ 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)