* [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free
@ 2017-01-17 9:29 Jim Lin
2017-09-01 17:25 ` Kees Cook
0 siblings, 1 reply; 3+ messages in thread
From: Jim Lin @ 2017-01-17 9:29 UTC (permalink / raw)
To: balbi; +Cc: linux-usb, linux-kernel, Jim Lin
When gadget is disconnected, running sequence is like this.
. composite_disconnect
. Call trace:
usb_string_copy+0xd0/0x128
gadget_config_name_configuration_store+0x4
gadget_config_name_attr_store+0x40/0x50
configfs_write_file+0x198/0x1f4
vfs_write+0x100/0x220
SyS_write+0x58/0xa8
. configfs_composite_unbind
. configfs_composite_bind
In configfs_composite_bind, it has
"cn->strings.s = cn->configuration;"
When usb_string_copy is invoked. it would
allocate memory, copy input string, release previous pointed memory space,
and use new allocated memory.
When gadget is connected, host sends down request to get information.
Call trace:
usb_gadget_get_string+0xec/0x168
lookup_string+0x64/0x98
composite_setup+0xa34/0x1ee8
android_setup+0xb4/0x140
If gadget is disconnected and connected quickly, in the failed case,
cn->configuration memory has been released by usb_string_copy kfree but
configfs_composite_bind hasn't been run in time to assign new allocated
"cn->configuration" pointer to "cn->strings.s".
When "strlen(s->s) of usb_gadget_get_string is being executed, the dangling
memory is accessed, "BUG: KASAN: use-after-free" error occurs.
Signed-off-by: Jim Lin <jilin@nvidia.com>
---
Changes in v2:
Rephrase commit description
drivers/usb/gadget/configfs.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 78c4497..39fea62 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -106,6 +106,9 @@ struct gadget_config_name {
struct list_head list;
};
+#define MAX_USB_STRING_LEN 126
+#define MAX_USB_STRING_WITH_NULL_LEN (MAX_USB_STRING_LEN+1)
+
static int usb_string_copy(const char *s, char **s_copy)
{
int ret;
@@ -115,12 +118,16 @@ static int usb_string_copy(const char *s, char **s_copy)
if (ret > 126)
return -EOVERFLOW;
- str = kstrdup(s, GFP_KERNEL);
- if (!str)
- return -ENOMEM;
+ if (copy) {
+ str = copy;
+ } else {
+ str = kmalloc(MAX_USB_STRING_WITH_NULL_LEN, GFP_KERNEL);
+ if (!str)
+ return -ENOMEM;
+ }
+ strcpy(str, s);
if (str[ret - 1] == '\n')
str[ret - 1] = '\0';
- kfree(copy);
*s_copy = str;
return 0;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free
2017-01-17 9:29 [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free Jim Lin
@ 2017-09-01 17:25 ` Kees Cook
[not found] ` <CACCg+XODNWZ5FMYLxQaLpspjDYKB_3Uzx1zC-q0dAo2g8xpOYw@mail.gmail.com>
0 siblings, 1 reply; 3+ messages in thread
From: Kees Cook @ 2017-09-01 17:25 UTC (permalink / raw)
To: Jim Lin; +Cc: Felipe Balbi, linux-usb, LKML, Greg KH, Steve Beattie
On Tue, Jan 17, 2017 at 1:29 AM, Jim Lin <jilin@nvidia.com> wrote:
> When gadget is disconnected, running sequence is like this.
> . composite_disconnect
> . Call trace:
> usb_string_copy+0xd0/0x128
> gadget_config_name_configuration_store+0x4
> gadget_config_name_attr_store+0x40/0x50
> configfs_write_file+0x198/0x1f4
> vfs_write+0x100/0x220
> SyS_write+0x58/0xa8
> . configfs_composite_unbind
> . configfs_composite_bind
>
> In configfs_composite_bind, it has
> "cn->strings.s = cn->configuration;"
>
> When usb_string_copy is invoked. it would
> allocate memory, copy input string, release previous pointed memory space,
> and use new allocated memory.
>
> When gadget is connected, host sends down request to get information.
> Call trace:
> usb_gadget_get_string+0xec/0x168
> lookup_string+0x64/0x98
> composite_setup+0xa34/0x1ee8
> android_setup+0xb4/0x140
>
> If gadget is disconnected and connected quickly, in the failed case,
> cn->configuration memory has been released by usb_string_copy kfree but
> configfs_composite_bind hasn't been run in time to assign new allocated
> "cn->configuration" pointer to "cn->strings.s".
>
> When "strlen(s->s) of usb_gadget_get_string is being executed, the dangling
> memory is accessed, "BUG: KASAN: use-after-free" error occurs.
>
> Signed-off-by: Jim Lin <jilin@nvidia.com>
Hi! What's the current state of this patch?
> ---
> Changes in v2:
> Rephrase commit description
>
> drivers/usb/gadget/configfs.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> index 78c4497..39fea62 100644
> --- a/drivers/usb/gadget/configfs.c
> +++ b/drivers/usb/gadget/configfs.c
> @@ -106,6 +106,9 @@ struct gadget_config_name {
> struct list_head list;
> };
>
> +#define MAX_USB_STRING_LEN 126
> +#define MAX_USB_STRING_WITH_NULL_LEN (MAX_USB_STRING_LEN+1)
> +
> static int usb_string_copy(const char *s, char **s_copy)
> {
> int ret;
> @@ -115,12 +118,16 @@ static int usb_string_copy(const char *s, char **s_copy)
> if (ret > 126)
This should be MAX_USB_STRING_LEN, yes?
> return -EOVERFLOW;
>
> - str = kstrdup(s, GFP_KERNEL);
> - if (!str)
> - return -ENOMEM;
> + if (copy) {
> + str = copy;
> + } else {
> + str = kmalloc(MAX_USB_STRING_WITH_NULL_LEN, GFP_KERNEL);
> + if (!str)
> + return -ENOMEM;
> + }
> + strcpy(str, s);
> if (str[ret - 1] == '\n')
> str[ret - 1] = '\0';
> - kfree(copy);
> *s_copy = str;
> return 0;
> }
> --
> 2.7.4
>
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free
[not found] ` <CACCg+XODNWZ5FMYLxQaLpspjDYKB_3Uzx1zC-q0dAo2g8xpOYw@mail.gmail.com>
@ 2020-06-11 4:24 ` Macpaul Lin
0 siblings, 0 replies; 3+ messages in thread
From: Macpaul Lin @ 2020-06-11 4:24 UTC (permalink / raw)
To: Macpaul Lin, Jim Lin, Felipe Balbi, linux-usb, linux-kernel,
Greg KH, Steve Beattie, Kees Cook, Steve Beattie, Siqi Lin
On Thu, 2017-09-01 at 10:25:32 -0700, Kees Cook wrote:
> Subject: Re: [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free
> To: Jim Lin <jilin@nvidia.com>
> Cc: Felipe Balbi <balbi@kernel.org>, <linux-usb@vger.kernel.org>, LKML
> <linux-kernel@vger.kernel.org>, Greg KH <gregkh@linuxfoundation.org>,
> Steve Beattie <steve.beattie@canonical.com>
>
>
> On Tue, Jan 17, 2017 at 1:29 AM, Jim Lin <jilin@nvidia.com> wrote:
> > When gadget is disconnected, running sequence is like this.
> > . composite_disconnect
> > . Call trace:
> > usb_string_copy+0xd0/0x128
> > gadget_config_name_configuration_store+0x4
> > gadget_config_name_attr_store+0x40/0x50
> > configfs_write_file+0x198/0x1f4
> > vfs_write+0x100/0x220
> > SyS_write+0x58/0xa8
> > . configfs_composite_unbind
> > . configfs_composite_bind
> >
> > In configfs_composite_bind, it has
> > "cn->strings.s = cn->configuration;"
> >
> > When usb_string_copy is invoked. it would
> > allocate memory, copy input string, release previous pointed memory space,
> > and use new allocated memory.
> >
> > When gadget is connected, host sends down request to get information.
> > Call trace:
> > usb_gadget_get_string+0xec/0x168
> > lookup_string+0x64/0x98
> > composite_setup+0xa34/0x1ee8
> > android_setup+0xb4/0x140
> >
> > If gadget is disconnected and connected quickly, in the failed case,
> > cn->configuration memory has been released by usb_string_copy kfree but
> > configfs_composite_bind hasn't been run in time to assign new allocated
> > "cn->configuration" pointer to "cn->strings.s".
> >
> > When "strlen(s->s) of usb_gadget_get_string is being executed, the dangling
> > memory is accessed, "BUG: KASAN: use-after-free" error occurs.
> >
> > Signed-off-by: Jim Lin <jilin@nvidia.com>
>
> Hi! What's the current state of this patch?
Mediatek is using this bug fix in Android kernel 3.18, 4.4, 4.9, 4.14
and 4.19. Kernel code nowadays.
Since there are news that Google is planning to use Generic Kernel Image
(GKI) for future Android. Should this patch be refined and adapt into
Linux?
Dear Jim and Siqi, according to Felipe's mail before, do you have
environments to test it on a Linux environment like on PC? Maybe on some
embedded environment not using Android or Chromium OS? I don't have that
kind of environment in my office hence I just couldn't provide a help to
do the test.
> > ---
> > Changes in v2:
> > Rephrase commit description
> >
> > drivers/usb/gadget/configfs.c | 15 +++++++++++----
> > 1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> > index 78c4497..39fea62 100644
> > --- a/drivers/usb/gadget/configfs.c
> > +++ b/drivers/usb/gadget/configfs.c
> > @@ -106,6 +106,9 @@ struct gadget_config_name {
> > struct list_head list;
> > };
> >
> > +#define MAX_USB_STRING_LEN 126
> > +#define MAX_USB_STRING_WITH_NULL_LEN (MAX_USB_STRING_LEN+1)
> > +
> > static int usb_string_copy(const char *s, char **s_copy)
> > {
> > int ret;
> > @@ -115,12 +118,16 @@ static int usb_string_copy(const char *s, char **s_copy)
> > if (ret > 126)
>
> This should be MAX_USB_STRING_LEN, yes?
>
> > return -EOVERFLOW;
> >
> > - str = kstrdup(s, GFP_KERNEL);
> > - if (!str)
> > - return -ENOMEM;
> > + if (copy) {
> > + str = copy;
> > + } else {
> > + str = kmalloc(MAX_USB_STRING_WITH_NULL_LEN, GFP_KERNEL);
> > + if (!str)
> > + return -ENOMEM;
> > + }
> > + strcpy(str, s);
> > if (str[ret - 1] == '\n')
> > str[ret - 1] = '\0';
> > - kfree(copy);
> > *s_copy = str;
> > return 0;
> > }
> > --
> > 2.7.4
> >
>
> -Kees
Thank you very much.
Macpaul Lin
^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-01-17 9:29 [PATCH v2] usb: gadget: configfs: Fix KASAN use-after-free Jim Lin
2017-09-01 17:25 ` Kees Cook
[not found] ` <CACCg+XODNWZ5FMYLxQaLpspjDYKB_3Uzx1zC-q0dAo2g8xpOYw@mail.gmail.com>
2020-06-11 4:24 ` Macpaul Lin
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