diff options
| author | Will Deacon <will@kernel.org> | 2019-10-02 15:42:06 +0300 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2019-10-03 15:50:16 +0300 |
| commit | be4c60b563edee3712d392aaeb0943a768df7023 (patch) | |
| tree | ac614e11eb968b58841fe4c887d13f2d5fe5fba7 /drivers/pinctrl/devicetree.c | |
| parent | 09107a51b096fbac3ea32d9ea150ddf029cbc358 (diff) | |
| download | linux-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.c | 25 |
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) |