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 ocfs2_replay_map.

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

Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: ocfs2-devel@lists.linux.dev
Cc: llvm@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/ocfs2/journal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index ce215565d061..604fea3a26ff 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -90,7 +90,7 @@ enum ocfs2_replay_state {
 struct ocfs2_replay_map {
 	unsigned int rm_slots;
 	enum ocfs2_replay_state rm_state;
-	unsigned char rm_replay_slots[];
+	unsigned char rm_replay_slots[] __counted_by(rm_slots);
 };
 
 static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)
-- 
2.34.1

On 9/23/23 1:49 AM, 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 ocfs2_replay_map.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Mark Fasheh <mark@fasheh.com>
> Cc: Joel Becker <jlbec@evilplan.org>
> Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Tom Rix <trix@redhat.com>
> Cc: ocfs2-devel@lists.linux.dev
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
> ---
>  fs/ocfs2/journal.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index ce215565d061..604fea3a26ff 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -90,7 +90,7 @@ enum ocfs2_replay_state {
>  struct ocfs2_replay_map {
>  	unsigned int rm_slots;
>  	enum ocfs2_replay_state rm_state;
> -	unsigned char rm_replay_slots[];
> +	unsigned char rm_replay_slots[] __counted_by(rm_slots);
>  };
>  
>  static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)

On 9/22/23 11:49, 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 ocfs2_replay_map.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Mark Fasheh <mark@fasheh.com>
> Cc: Joel Becker <jlbec@evilplan.org>
> Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Tom Rix <trix@redhat.com>
> Cc: ocfs2-devel@lists.linux.dev
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
-- 
Gustavo

> ---
>   fs/ocfs2/journal.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index ce215565d061..604fea3a26ff 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -90,7 +90,7 @@ enum ocfs2_replay_state {
>   struct ocfs2_replay_map {
>   	unsigned int rm_slots;
>   	enum ocfs2_replay_state rm_state;
> -	unsigned char rm_replay_slots[];
> +	unsigned char rm_replay_slots[] __counted_by(rm_slots);
>   };
>   
>   static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)