* [PATCH v2] usb: core: fix quirks_param_set() writing to a const pointer
@ 2020-07-07 12:51 Kars Mulder
2020-07-07 13:18 ` Greg Kroah-Hartman
0 siblings, 1 reply; 2+ messages in thread
From: Kars Mulder @ 2020-07-07 12:51 UTC (permalink / raw)
To: linux-kernel, linux-usb
Cc: Pavel Machek, David Laight, Greg Kroah-Hartman, Kai-Heng Feng,
Andy Shevchenko, Oliver Neukum
The function quirks_param_set() takes as argument a const char* pointer
to the new value of the usbcore.quirks parameter. It then casts this
pointer to a non-const char* pointer and passes it to the strsep()
function, which overwrites the value.
Fix this by creating a copy of the value using kstrdup() and letting
that copy be written to by strsep().
Fixes: 027bd6cafd9a ("usb: core: Add "quirks" parameter for usbcore")
Signed-off-by: Kars Mulder <kerneldev@karsmulder.nl>
---
drivers/usb/core/quirks.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index e0b77674869c..c96c50faccf7 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -25,17 +25,23 @@ static unsigned int quirk_count;
static char quirks_param[128];
-static int quirks_param_set(const char *val, const struct kernel_param *kp)
+static int quirks_param_set(const char *value, const struct kernel_param *kp)
{
- char *p, *field;
+ char *val, *p, *field;
u16 vid, pid;
u32 flags;
size_t i;
int err;
+ val = kstrdup(value, GFP_KERNEL);
+ if (!val)
+ return -ENOMEM;
+
err = param_set_copystring(val, kp);
- if (err)
+ if (err) {
+ kfree(val);
return err;
+ }
mutex_lock(&quirk_mutex);
@@ -60,10 +66,11 @@ static int quirks_param_set(const char *val, const struct kernel_param *kp)
if (!quirk_list) {
quirk_count = 0;
mutex_unlock(&quirk_mutex);
+ kfree(val);
return -ENOMEM;
}
- for (i = 0, p = (char *)val; p && *p;) {
+ for (i = 0, p = val; p && *p;) {
/* Each entry consists of VID:PID:flags */
field = strsep(&p, ":");
if (!field)
@@ -144,6 +151,7 @@ static int quirks_param_set(const char *val, const struct kernel_param *kp)
unlock:
mutex_unlock(&quirk_mutex);
+ kfree(val);
return 0;
}
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] usb: core: fix quirks_param_set() writing to a const pointer
2020-07-07 12:51 [PATCH v2] usb: core: fix quirks_param_set() writing to a const pointer Kars Mulder
@ 2020-07-07 13:18 ` Greg Kroah-Hartman
0 siblings, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2020-07-07 13:18 UTC (permalink / raw)
To: Kars Mulder
Cc: linux-kernel, linux-usb, Pavel Machek, David Laight,
Kai-Heng Feng, Andy Shevchenko, Oliver Neukum
On Tue, Jul 07, 2020 at 02:51:02PM +0200, Kars Mulder wrote:
> The function quirks_param_set() takes as argument a const char* pointer
> to the new value of the usbcore.quirks parameter. It then casts this
> pointer to a non-const char* pointer and passes it to the strsep()
> function, which overwrites the value.
>
> Fix this by creating a copy of the value using kstrdup() and letting
> that copy be written to by strsep().
>
> Fixes: 027bd6cafd9a ("usb: core: Add "quirks" parameter for usbcore")
> Signed-off-by: Kars Mulder <kerneldev@karsmulder.nl>
>
> ---
> drivers/usb/core/quirks.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
What changed from v1? Always put that below the --- line like the
documentation asks.
Please fix up and resend a v3.
thanks,
greg k-h
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