[PATCH v2] driver core: Add __alloc_size hint to devm allocators

[Kees Cook]

Mark the devm_*alloc()-family of allocations with appropriate
__alloc_size()/__realloc_size() hints so the compiler can attempt to
reason about buffer lengths from allocations.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Rasmus Villemoes <rasmus.villemoes@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Nishanth Menon <nm@xxxxxx>
Cc: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Won Chung <wonchung@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
I'm hoping to carry this via the hardening tree so I can add a
KUnit test that depends on it...
v2: use __realloc_size instead of __alloc_size
v1: https://lore.kernel.org/linux-hardening/20221018073430.never.551-kees@xxxxxxxxxx/
---
 include/linux/device.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/device.h b/include/linux/device.h
index 424b55df0272..5e4cd857e74f 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -197,9 +197,9 @@ void devres_remove_group(struct device *dev, void *id);
 int devres_release_group(struct device *dev, void *id);
 
 /* managed devm_k.alloc/kfree for device drivers */
-void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc;
+void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __alloc_size(2);
 void *devm_krealloc(struct device *dev, void *ptr, size_t size,
-		    gfp_t gfp) __must_check;
+		    gfp_t gfp) __must_check __realloc_size(3);
 __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp,
 				     const char *fmt, va_list ap) __malloc;
 __printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp,
@@ -226,7 +226,8 @@ static inline void *devm_kcalloc(struct device *dev,
 void devm_kfree(struct device *dev, const void *p);
 char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp) __malloc;
 const char *devm_kstrdup_const(struct device *dev, const char *s, gfp_t gfp);
-void *devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp);
+void *devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp)
+	__realloc_size(3);
 
 unsigned long devm_get_free_pages(struct device *dev,
 				  gfp_t gfp_mask, unsigned int order);
-- 
2.34.1