* [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent()
@ 2015-10-27 15:46 Nathan Fontenot
2015-10-27 15:52 ` Andy Shevchenko
2015-11-02 9:41 ` [v2] " Michael Ellerman
0 siblings, 2 replies; 3+ messages in thread
From: Nathan Fontenot @ 2015-10-27 15:46 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Andy Shevchenko
Commit a030e1e4bbd085bbcfd0a23f8d355fcd41f39bed make a change to use
kstrndup() instead of kmalloc() + strlcpy() in the pseries_of_derive_parent()
routine that introduces a subtle change in the parent path name generated.
The kstrndup() routine will copy n characters followed by a terminating null,
whereas strlcpy() will copy n-1 characters and add a terminating null.
This slight difference results in having a parent path that includes the
tailing '/' character, "/cpus/" vs. "/cpus". This then causes the subsequent
call to of_find_node_by_path() to fail, and in the case of DLPAR add
operations the DLPAR request fails.
This patch decrements the pointer returned from kbasename() to point to the
'/' character before the base name instead of the base name. This then
adjusts the string length calculations to not include the trailing '/'
in the parent path name.
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
---
Updates for v2: Decrement the pointer returned from kbasename() instead
of subtracting 1 when calculating the string length.
arch/powerpc/platforms/pseries/of_helpers.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/of_helpers.c b/arch/powerpc/platforms/pseries/of_helpers.c
index 4417afe..2798933 100644
--- a/arch/powerpc/platforms/pseries/of_helpers.c
+++ b/arch/powerpc/platforms/pseries/of_helpers.c
@@ -17,13 +17,16 @@ struct device_node *pseries_of_derive_parent(const char *path)
{
struct device_node *parent;
char *parent_path = "/";
- const char *tail = kbasename(path);
+ const char *tail;
+
+ /* We do not want the trailing '/' character */
+ tail = kbasename(path) - 1;
/* reject if path is "/" */
if (!strcmp(path, "/"))
return ERR_PTR(-EINVAL);
- if (tail > path + 1) {
+ if (tail > path) {
parent_path = kstrndup(path, tail - path, GFP_KERNEL);
if (!parent_path)
return ERR_PTR(-ENOMEM);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent()
2015-10-27 15:46 [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent() Nathan Fontenot
@ 2015-10-27 15:52 ` Andy Shevchenko
2015-11-02 9:41 ` [v2] " Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Andy Shevchenko @ 2015-10-27 15:52 UTC (permalink / raw)
To: Nathan Fontenot, linuxppc-dev
On Tue, 2015-10-27 at 10:46 -0500, Nathan Fontenot wrote:
> Commit a030e1e4bbd085bbcfd0a23f8d355fcd41f39bed make a change to use
> kstrndup() instead of kmalloc() + strlcpy() in the
> pseries_of_derive_parent()
> routine that introduces a subtle change in the parent path name
> generated.
> The kstrndup() routine will copy n characters followed by a
> terminating null,
> whereas strlcpy() will copy n-1 characters and add a terminating
> null.
>
> This slight difference results in having a parent path that includes
> the
> tailing '/' character, "/cpus/" vs. "/cpus". This then causes the
> subsequent
> call to of_find_node_by_path() to fail, and in the case of DLPAR add
> operations the DLPAR request fails.
>
> This patch decrements the pointer returned from kbasename() to point
> to the
> '/' character before the base name instead of the base name. This
> then
> adjusts the string length calculations to not include the trailing
> '/'
> in the parent path name.
>
> Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>
> Updates for v2: Decrement the pointer returned from kbasename()
> instead
> of subtracting 1 when calculating the string length.
>
> arch/powerpc/platforms/pseries/of_helpers.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/of_helpers.c
> b/arch/powerpc/platforms/pseries/of_helpers.c
> index 4417afe..2798933 100644
> --- a/arch/powerpc/platforms/pseries/of_helpers.c
> +++ b/arch/powerpc/platforms/pseries/of_helpers.c
> @@ -17,13 +17,16 @@ struct device_node
> *pseries_of_derive_parent(const char *path)
> {
> struct device_node *parent;
> char *parent_path = "/";
> - const char *tail = kbasename(path);
> + const char *tail;
> +
> + /* We do not want the trailing '/' character */
> + tail = kbasename(path) - 1;
>
> /* reject if path is "/" */
> if (!strcmp(path, "/"))
> return ERR_PTR(-EINVAL);
>
> - if (tail > path + 1) {
> + if (tail > path) {
> parent_path = kstrndup(path, tail - path,
> GFP_KERNEL);
> if (!parent_path)
> return ERR_PTR(-ENOMEM);
>
--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [v2] powerpc/pseries: Correct string length in pseries_of_derive_parent()
2015-10-27 15:46 [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent() Nathan Fontenot
2015-10-27 15:52 ` Andy Shevchenko
@ 2015-11-02 9:41 ` Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Michael Ellerman @ 2015-11-02 9:41 UTC (permalink / raw)
To: Nathan Fontenot, linuxppc-dev; +Cc: Andy Shevchenko
On Tue, 2015-27-10 at 15:46:47 UTC, Nathan Fontenot wrote:
> Commit a030e1e4bbd085bbcfd0a23f8d355fcd41f39bed make a change to use
> kstrndup() instead of kmalloc() + strlcpy() in the pseries_of_derive_parent()
> routine that introduces a subtle change in the parent path name generated.
> The kstrndup() routine will copy n characters followed by a terminating null,
> whereas strlcpy() will copy n-1 characters and add a terminating null.
>
> This slight difference results in having a parent path that includes the
> tailing '/' character, "/cpus/" vs. "/cpus". This then causes the subsequent
> call to of_find_node_by_path() to fail, and in the case of DLPAR add
> operations the DLPAR request fails.
>
> This patch decrements the pointer returned from kbasename() to point to the
> '/' character before the base name instead of the base name. This then
> adjusts the string length calculations to not include the trailing '/'
> in the parent path name.
>
> Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/f755ecfb8cec7b19dff84295
cheers
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-10-27 15:46 [PATCH v2] powerpc/pseries: Correct string length in pseries_of_derive_parent() Nathan Fontenot
2015-10-27 15:52 ` Andy Shevchenko
2015-11-02 9:41 ` [v2] " Michael Ellerman
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