On Wed, 14 Jan 2026 14:35:55 +0000 Al Viro <[email protected]> wrote:
> On Wed, Jan 14, 2026 at 10:41:55AM +0000, David Laight wrote: > > On Wed, 14 Jan 2026 04:33:10 +0000 > > Al Viro <[email protected]> wrote: > > > > > ... it's a filesystem type name. > > > > > > Signed-off-by: Al Viro <[email protected]> > > > --- > > > fs/filesystems.c | 9 +++------ > > > 1 file changed, 3 insertions(+), 6 deletions(-) > > > > > > diff --git a/fs/filesystems.c b/fs/filesystems.c > > > index 95e5256821a5..0c7d2b7ac26c 100644 > > > --- a/fs/filesystems.c > > > +++ b/fs/filesystems.c > > > @@ -132,24 +132,21 @@ EXPORT_SYMBOL(unregister_filesystem); > > > static int fs_index(const char __user * __name) > > > { > > > struct file_system_type * tmp; > > > - struct filename *name; > > > + char *name __free(kfree) = strndup_user(__name, PATH_MAX); > > > int err, index; > > > > > > - name = getname(__name); > > > - err = PTR_ERR(name); > > > if (IS_ERR(name)) > > > - return err; > > > + return PTR_ERR(name); > > > > Doesn't that end up calling kfree(name) and the check in kfree() doesn't > > seem to exclude error values. > > include/linux/slab.h:523:DEFINE_FREE(kfree, void *, if (!IS_ERR_OR_NULL(_T)) > kfree(_T)) > > kfree() the function won't be even called in that case... I wasn't expecting the code to be optimised for the pointer being invalid. I guess one of the defines does a 'dance' so that the pointer can be returned without kfree() being called - and that needs a check in the function itself. (I'm sure I remember something about the compiler optimising at all away.) Perhaps the test could be: if (!statically_true(IS_ERR_OR_NULL(_T)) kfree(_T) adjusting the check in kfree() to ignore -4096..16 not just 0..16. That should reduce code size without slowing down the 'normal' paths and possibly speeding up the error paths. David
