[v2] usb: gadget: configfs: Fix use-after-free issue with udc_name
diff mbox series

Message ID 1595040303-23046-1-git-send-email-macpaul.lin@mediatek.com
State New
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Series
  • [v2] usb: gadget: configfs: Fix use-after-free issue with udc_name
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Commit Message

Macpaul Lin July 18, 2020, 2:45 a.m. UTC
From: Eddie Hung <eddie.hung@mediatek.com>

There is a use-after-free issue, if access udc_name
in function gadget_dev_desc_UDC_store after another context
free udc_name in function unregister_gadget.

Context 1:
gadget_dev_desc_UDC_store()->unregister_gadget()->
free udc_name->set udc_name to NULL

Context 2:
gadget_dev_desc_UDC_show()-> access udc_name

Call trace:
dump_backtrace+0x0/0x340
show_stack+0x14/0x1c
dump_stack+0xe4/0x134
print_address_description+0x78/0x478
__kasan_report+0x270/0x2ec
kasan_report+0x10/0x18
__asan_report_load1_noabort+0x18/0x20
string+0xf4/0x138
vsnprintf+0x428/0x14d0
sprintf+0xe4/0x12c
gadget_dev_desc_UDC_show+0x54/0x64
configfs_read_file+0x210/0x3a0
__vfs_read+0xf0/0x49c
vfs_read+0x130/0x2b4
SyS_read+0x114/0x208
el0_svc_naked+0x34/0x38

Add mutex_lock to protect this kind of scenario.

Signed-off-by: Eddie Hung <eddie.hung@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Cc: stable@vger.kernel.org
---
Changes for v2:
  - Fix typo %s/contex/context, Thanks Peter.

 drivers/usb/gadget/configfs.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Comments

Macpaul Lin July 18, 2020, 2:58 a.m. UTC | #1
On Sat, 2020-07-18 at 10:45 +0800, Macpaul Lin wrote:
> From: Eddie Hung <eddie.hung@mediatek.com>
> 

Well, it's strange, I simply replaced the uploader's name to my
colleague, git send-email pop up this line automatically.

Shouldn't I do that kind of change. It did not happened before.
Do I need to change it back and update patch v3?
 
> There is a use-after-free issue, if access udc_name
> in function gadget_dev_desc_UDC_store after another context
> free udc_name in function unregister_gadget.
> 
> Context 1:
> gadget_dev_desc_UDC_store()->unregister_gadget()->
> free udc_name->set udc_name to NULL
> 
> Context 2:
> gadget_dev_desc_UDC_show()-> access udc_name
> 
> Call trace:
> dump_backtrace+0x0/0x340
> show_stack+0x14/0x1c
> dump_stack+0xe4/0x134
> print_address_description+0x78/0x478
> __kasan_report+0x270/0x2ec
> kasan_report+0x10/0x18
> __asan_report_load1_noabort+0x18/0x20
> string+0xf4/0x138
> vsnprintf+0x428/0x14d0
> sprintf+0xe4/0x12c
> gadget_dev_desc_UDC_show+0x54/0x64
> configfs_read_file+0x210/0x3a0
> __vfs_read+0xf0/0x49c
> vfs_read+0x130/0x2b4
> SyS_read+0x114/0x208
> el0_svc_naked+0x34/0x38
> 
> Add mutex_lock to protect this kind of scenario.
> 
> Signed-off-by: Eddie Hung <eddie.hung@mediatek.com>
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> Reviewed-by: Peter Chen <peter.chen@nxp.com>
> Cc: stable@vger.kernel.org
> ---
> Changes for v2:
>   - Fix typo %s/contex/context, Thanks Peter.
> 
>  drivers/usb/gadget/configfs.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

Thanks.
Macpaul Lin
Greg KH July 21, 2020, 11:33 a.m. UTC | #2
On Sat, Jul 18, 2020 at 10:58:53AM +0800, Macpaul Lin wrote:
> On Sat, 2020-07-18 at 10:45 +0800, Macpaul Lin wrote:
> > From: Eddie Hung <eddie.hung@mediatek.com>
> > 
> 
> Well, it's strange, I simply replaced the uploader's name to my
> colleague, git send-email pop up this line automatically.
> 
> Shouldn't I do that kind of change. It did not happened before.
> Do I need to change it back and update patch v3?

Who is the real author of this, Eddie or you?  If Eddie, this is
correct, if you, it is not.

thanks,

greg k-h
Macpaul Lin July 22, 2020, 1:59 a.m. UTC | #3
On Tue, 2020-07-21 at 13:33 +0200, Greg Kroah-Hartman wrote:
> On Sat, Jul 18, 2020 at 10:58:53AM +0800, Macpaul Lin wrote:
> > On Sat, 2020-07-18 at 10:45 +0800, Macpaul Lin wrote:
> > > From: Eddie Hung <eddie.hung@mediatek.com>
> > > 
> > 
> > Well, it's strange, I simply replaced the uploader's name to my
> > colleague, git send-email pop up this line automatically.
> > 
> > Shouldn't I do that kind of change. It did not happened before.
> > Do I need to change it back and update patch v3?
> 
> Who is the real author of this, Eddie or you?  If Eddie, this is
> correct, if you, it is not.
> 
> thanks,
> 
> greg k-h

It is Eddie! I just changed the uploader to the correct author from my
working tree!
Thanks!

Regards,
Macpaul Lin

Patch
diff mbox series

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 9dc06a4e1b30..21110b2865b9 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -221,9 +221,16 @@  static ssize_t gadget_dev_desc_bcdUSB_store(struct config_item *item,
 
 static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page)
 {
-	char *udc_name = to_gadget_info(item)->composite.gadget_driver.udc_name;
+	struct gadget_info *gi = to_gadget_info(item);
+	char *udc_name;
+	int ret;
+
+	mutex_lock(&gi->lock);
+	udc_name = gi->composite.gadget_driver.udc_name;
+	ret = sprintf(page, "%s\n", udc_name ?: "");
+	mutex_unlock(&gi->lock);
 
-	return sprintf(page, "%s\n", udc_name ?: "");
+	return ret;
 }
 
 static int unregister_gadget(struct gadget_info *gi)