Commit edb16da3 authored Apr 22, 2019 by Venkata Narendra Kumar Gutta Committed by Greg Kroah-Hartman Apr 25, 2019

driver core: platform: Fix the usage of platform device name(pdev->name)



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>

parent 70283454

drivers/base/platform.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -890,7 +890,7 @@ 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;
		}
		@@ -966,7 +966,7 @@ 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;
		}

		@@ -975,7 +975,7 @@ 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;
		}
		@@ -1019,7 +1019,7 @@ 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