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* [PATCH] eventfs: Use ERR_CAST() in eventfs_create_events_dir()
@ 2023-10-18 18:10 Nathan Chancellor
  2023-10-18 18:14 ` Kees Cook
  0 siblings, 1 reply; 2+ messages in thread
From: Nathan Chancellor @ 2023-10-18 18:10 UTC (permalink / raw)
  To: rostedt, mhiramat
  Cc: keescook, ndesaulniers, trix, linux-kernel, linux-trace-kernel,
	llvm, patches, Nathan Chancellor

When building with clang and CONFIG_RANDSTRUCT_FULL=y, there is an error
due to a cast in eventfs_create_events_dir():

  fs/tracefs/event_inode.c:734:10: error: casting from randomized structure pointer type 'struct dentry *' to 'struct eventfs_inode *'
    734 |                 return (struct eventfs_inode *)dentry;
        |                        ^
  1 error generated.

Use the ERR_CAST() function to resolve the error, as it was designed for
this exact situation (casting an error pointer to another type).

Closes: https://github.com/ClangBuiltLinux/linux/issues/1947
Fixes: 5790b1fb3d67 ("eventfs: Remove eventfs_file and just use eventfs_inode")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 fs/tracefs/event_inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 1ccd100bc565..9f19b6608954 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -731,7 +731,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
 		return NULL;
 
 	if (IS_ERR(dentry))
-		return (struct eventfs_inode *)dentry;
+		return ERR_CAST(dentry);
 
 	ei = kzalloc(sizeof(*ei), GFP_KERNEL);
 	if (!ei)

---
base-commit: 5ddd8baa4857709b4e5d84b376d735152851955b
change-id: 20231018-ftrace-fix-clang-randstruct-0cb6899523ac

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] eventfs: Use ERR_CAST() in eventfs_create_events_dir()
  2023-10-18 18:10 [PATCH] eventfs: Use ERR_CAST() in eventfs_create_events_dir() Nathan Chancellor
@ 2023-10-18 18:14 ` Kees Cook
  0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2023-10-18 18:14 UTC (permalink / raw)
  To: Nathan Chancellor
  Cc: rostedt, mhiramat, ndesaulniers, trix, linux-kernel,
	linux-trace-kernel, llvm, patches

On Wed, Oct 18, 2023 at 11:10:31AM -0700, Nathan Chancellor wrote:
> When building with clang and CONFIG_RANDSTRUCT_FULL=y, there is an error
> due to a cast in eventfs_create_events_dir():
> 
>   fs/tracefs/event_inode.c:734:10: error: casting from randomized structure pointer type 'struct dentry *' to 'struct eventfs_inode *'
>     734 |                 return (struct eventfs_inode *)dentry;
>         |                        ^
>   1 error generated.
> 
> Use the ERR_CAST() function to resolve the error, as it was designed for
> this exact situation (casting an error pointer to another type).
> 
> Closes: https://github.com/ClangBuiltLinux/linux/issues/1947
> Fixes: 5790b1fb3d67 ("eventfs: Remove eventfs_file and just use eventfs_inode")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Yes, please. That's the correct method to do such casts. Thanks!

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

^ permalink raw reply	[flat|nested] 2+ messages in thread

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