[PATCH AUTOSEL 4.9 021/114] driver core: platform: Fix the usage of platform device name(pdev->name)

Sasha Levin
2019-05-22T19:35:25Z

From: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>

[ Upstream commit edb16da34b084c66763f29bee42b4e6bb33c3d66 ]

Platform core is using pdev->name as the platform device name to do
the binding of the devices with the drivers. But, when the platform
driver overrides the platform device name with dev_set_name(),
the pdev->name is pointing to a location which is freed and becomes
an invalid parameter to do the binding match.

use-after-free instance:

[ 33.325013] BUG: KASAN: use-after-free in strcmp+0x8c/0xb0
[ 33.330646] Read of size 1 at addr ffffffc10beae600 by task modprobe
[ 33.339068] CPU: 5 PID: 518 Comm: modprobe Tainted:
G S W O 4.19.30+ #3
[ 33.346835] Hardware name: MTP (DT)
[ 33.350419] Call trace:
[ 33.352941] dump_backtrace+0x0/0x3b8
[ 33.356713] show_stack+0x24/0x30
[ 33.360119] dump_stack+0x160/0x1d8
[ 33.363709] print_address_description+0x84/0x2e0
[ 33.368549] kasan_report+0x26c/0x2d0
[ 33.372322] __asan_report_load1_noabort+0x2c/0x38
[ 33.377248] strcmp+0x8c/0xb0
[ 33.380306] platform_match+0x70/0x1f8
[ 33.384168] __driver_attach+0x78/0x3a0
[ 33.388111] bus_for_each_dev+0x13c/0x1b8
[ 33.392237] driver_attach+0x4c/0x58
[ 33.395910] bus_add_driver+0x350/0x560
[ 33.399854] driver_register+0x23c/0x328
[ 33.403886] __platform_driver_register+0xd0/0xe0

So, use dev_name(&pdev->dev), which fetches the platform device name from
the kobject(dev->kobj->name) of the device instead of the pdev->name.

Signed-off-by: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/platform.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 14ff40371f013..ffa77b3df4ba2 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -845,7 +845,7 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
if (len != -ENODEV)
return len;

- len = snprintf(buf, PAGE_SIZE, "platform:%s\n", pdev->name);
+ len = snprintf(buf, PAGE_SIZE, "platform:%s\n", dev_name(&pdev->dev));

return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
}
@@ -921,7 +921,7 @@ static int platform_uevent(struct device *dev, struct kobj_uevent_env *env)
return rc;

add_uevent_var(env, "MODALIAS=%s%s", PLATFORM_MODULE_PREFIX,
- pdev->name);
+ dev_name(&pdev->dev));
return 0;
}

@@ -930,7 +930,7 @@ static const struct platform_device_id *platform_match_id(
struct platform_device *pdev)
{
while (id->name[0]) {
- if (strcmp(pdev->name, id->name) == 0) {
+ if (strcmp(dev_name(&pdev->dev), id->name) == 0) {
pdev->id_entry = id;
return id;
}
@@ -974,7 +974,7 @@ static int platform_match(struct device *dev, struct device_driver *drv)
return platform_match_id(pdrv->id_table, pdev) != NULL;

/* fall-back to driver name match */
- return (strcmp(pdev->name, drv->name) == 0);
+ return (strcmp(dev_name(&pdev->dev), drv->name) == 0);
}

#ifdef CONFIG_PM_SLEEP
--
2.20.1