Re: [PATCH 09/10] scsi: aic94xx: Remove snprintf() from sysfs call-backs and replace with sysfs_emit()

From: Kees Cook
Date: Sat Feb 10 2024 - 02:18:02 EST

On Thu, Feb 08, 2024 at 08:44:21AM +0000, Lee Jones wrote:
> Since snprintf() has the documented, but still rather strange trait of
> returning the length of the data that *would have been* written to the
> array if space were available, rather than the arguably more useful
> length of data *actually* written, it is usually considered wise to use
> something else instead in order to avoid confusion.
> In the case of sysfs call-backs, new wrappers exist that do just that.

Actually, a treewide replacement for snprintf(dst, PAGE_SIZE, ... to
sysfs_emit might be workable too. Here's the .cocci file I made quickly:

expression DST;

- snprintf(DST, PAGE_SIZE,
+ sysfs_emit(DST,

This produced almost 1000 changes:
118 files changed, 964 insertions(+), 958 deletions(-)

Some need some manual examination, like:

arch/powerpc/platforms/ps3/system-bus.c:modalias_show() does:

return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;

which isn't needed any more.


Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>


Kees Cook