[PATCH AUTOSEL 4.19 15/57] pinctrl: core: make sure strcmp() doesn't get a null parameter

Sasha Levin
2019-03-30T01:40:39Z

From: Yanjiang Jin <yanjiang.jin@hxt-semitech.com>

[ Upstream commit 54a58185bfafb5af5045fb8388c45daa373f90f3 ]

Some drivers, for example, QCOM's qdf2xxx, set groups[gpio].name only
when gpio is valid, and leave invalid gpio names as null.
If we want to access the sys node "pinconf-groups",
pinctrl_get_group_selector() -> get_group_name() may return a null
pointer if group_selector is invalid, then the below Kernel panic
would happen since strcmp() uses this null pointer to do comparison.

Unable to handle kernel NULL pointer dereference at ss 00000000
el:Internal error: Oops: 9600000[ 143.080279]
SMP
CPU: 19 PID: 2493 Comm: read_all Tainted: G O
.aarch64 #1
Hardware name: HXT Semiconductor HXT REP-2 System
PC is at strcmp+0x18/0x154
LR is at pinctrl_get_group_selector+0x6c/0xe8
Process read_all (pid: 2493, stack limit =
Call trace:
Exception stack
strcmp+0x18/0x154
pin_config_group_get+0x64/0xd8
pinconf_generic_dump_one+0xd8/0x1c0
pinconf_generic_dump_pins+0x94/0xc8
pinconf_groups_show+0xb4/0x104
seq_read+0x178/0x464
full_proxy_read+0x6c/0xac
__vfs_read+0x58/0x178
vfs_read+0x94/0x164
SyS_read+0x60/0xc0
__sys_trace_return+0x0/0x4
--[ end trace]--
Kernel panic - not syncing: Fatal exception

Signed-off-by: Yanjiang Jin <yanjiang.jin@hxt-semitech.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pinctrl/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index a3dd777e3ce8..c6ff4d5fa482 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -627,7 +627,7 @@ static int pinctrl_generic_group_name_to_selector(struct pinctrl_dev *pctldev,
while (selector < ngroups) {
const char *gname = ops->get_group_name(pctldev, selector);

- if (!strcmp(function, gname))
+ if (gname && !strcmp(function, gname))
return selector;

selector++;
@@ -743,7 +743,7 @@ int pinctrl_get_group_selector(struct pinctrl_dev *pctldev,
while (group_selector < ngroups) {
const char *gname = pctlops->get_group_name(pctldev,
group_selector);
- if (!strcmp(gname, pin_group)) {
+ if (gname && !strcmp(gname, pin_group)) {
dev_dbg(pctldev->dev,
"found group selector %u for %s\n",
group_selector,
--
2.19.1