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gcov: Annotate struct gcov_iterator with __counted_by

PATCH Applied Kees Cook 3 participants 3 messages Sep 22, 2023 – Oct 5, 2023 Gcov based kernel profiling

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Kees Cook

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PATCH 1/1 gcov: Annotate struct gcov_iterator with __counted_by

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 gcov_iterator.

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

Cc Peter Oberparleiter <[email protected]>
Signed-off-by Kees Cook <[email protected]>
---
 kernel/gcov/fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/gcov/fs.c +1 -1
index 5c3086cad8f9..01520689b57c 100644
@@ -99,7 +99,7 @@ struct gcov_iterator {
 	struct gcov_info *info;
 	size_t size;
 	loff_t pos;
-	char buffer[];
+	char buffer[] __counted_by(size);
 };
 
 /**
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 6 lines · 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).

Quoted 6 lines

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

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

Cc Peter Oberparleiter <[email protected]>
Signed-off-by Kees Cook <[email protected]>
Reviewed-by Gustavo A. R. Silva <[email protected]>

Thanks

Signature · 1 line
Gustavo
Quoted 17 lines
---
  kernel/gcov/fs.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
kernel/gcov/fs.c +1 -1
index 5c3086cad8f9..01520689b57c 100644
@@ -99,7 +99,7 @@ struct gcov_iterator {
  	struct gcov_info *info;
  	size_t size;
  	loff_t pos;
-	char buffer[];
+	char buffer[] __counted_by(size);
  };
 
  /**
maintainer Reviewed-by on v1 1/1
#2 lore raw
In reply to Kees Cook
Quoted 6 lines · 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).

Quoted 6 lines

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

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

Cc Peter Oberparleiter <[email protected]>
Signed-off-by Kees Cook <[email protected]>

Looks good to me!

Reviewed-by Peter Oberparleiter <[email protected]>

Andrew, could you add this patch via your tree?

Signature · 2 lines
Peter Oberparleiter
Linux on IBM Z Development - IBM Germany R&D