Re: [PATCH] afs: Annotate struct afs_permits with __counted_by

[Gustavo A. R. Silva]

On 9/15/23 14:14, Kees Cook wrote:

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct afs_permits.

[1] 
https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: David Howells 
Cc: Marc Dionne 
Cc: linux-...@lists.infradead.org
Signed-off-by: Kees Cook 


Reviewed-by: Gustavo A. R. Silva 

Thanks
--
Gustavo


---
  fs/afs/internal.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 07433a5349ca..469a717467a4 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -705,7 +705,7 @@ struct afs_permits {
refcount_t  usage;
unsigned short  nr_permits; /* Number of records */
boolinvalidated;/* Invalidated due to key 
change */
-   struct afs_permit   permits[];  /* List of permits sorted by 
key pointer */
+   struct afs_permit   permits[] __counted_by(nr_permits); /* List 
of permits sorted by key pointer */
  };
  
  /*

[PATCH] afs: Annotate struct afs_permits with __counted_by

[Kees Cook]

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct afs_permits.

[1] 
https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: David Howells 
Cc: Marc Dionne 
Cc: linux-...@lists.infradead.org
Signed-off-by: Kees Cook 
---
 fs/afs/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 07433a5349ca..469a717467a4 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -705,7 +705,7 @@ struct afs_permits {
refcount_t  usage;
unsigned short  nr_permits; /* Number of records */
boolinvalidated;/* Invalidated due to key 
change */
-   struct afs_permit   permits[];  /* List of permits sorted by 
key pointer */
+   struct afs_permit   permits[] __counted_by(nr_permits); /* List 
of permits sorted by key pointer */
 };
 
 /*
-- 
2.34.1