Re: [PATCH AUTOSEL 5.1 06/60] driver core: platform: Fix the usage of platform device name(pdev->name)

[Greg Kroah-Hartman]

On Tue, Jun 04, 2019 at 07:21:16PM -0400, Sasha Levin wrote:
> From: Venkata Narendra Kumar Gutta <vnkgutta@xxxxxxxxxxxxxx>
> 
> [ 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@xxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  drivers/base/platform.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Please drop this from everywhere as it was reverted from Linus's tree
because it causes big problems.

thanks,

greg k-h