| Message ID | 562F9C67.3040207@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
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); >
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
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);
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(-)