[PATCH] mm/slab: make __free(kfree) accept error pointers

[Dan Carpenter <dan.carpenter@linaro.org>]

Currently, if an automatically freed allocation is an error pointer that
will lead to a crash.  An example of this is in wm831x_gpio_dbg_show().

   171	char *label __free(kfree) = gpiochip_dup_line_label(chip, i);
   172	if (IS_ERR(label)) {
   173		dev_err(wm831x->dev, "Failed to duplicate label\n");
   174		continue;
   175  }

The auto clean up function should check for error pointers as well,
otherwise we're going to keep hitting issues like this.

Fixes: 54da6a092431 ("locking: Introduce __cleanup() based infrastructure")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
Obviously, the fixes tag isn't very fair but it will tell the -stable
tools how far to backport this.

 include/linux/slab.h  | 4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 4cc37ef22aae..5f5766219375 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -279,7 +279,7 @@ void kfree(const void *objp);
 void kfree_sensitive(const void *objp);
 size_t __ksize(const void *objp);
 
-DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
+DEFINE_FREE(kfree, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T))
 
 /**
  * ksize - Report actual allocation size of associated object
@@ -808,7 +808,7 @@ extern void *kvrealloc_noprof(const void *p, size_t oldsize, size_t newsize, gfp
 #define kvrealloc(...)				alloc_hooks(kvrealloc_noprof(__VA_ARGS__))
 
 extern void kvfree(const void *addr);
-DEFINE_FREE(kvfree, void *, if (_T) kvfree(_T))
+DEFINE_FREE(kvfree, void *, if (!IS_ERR_OR_NULL(_T)) kvfree(_T))
 
 extern void kvfree_sensitive(const void *addr, size_t len);
 
-- 
2.43.0