On Thu 27-08-26 04:17:29, Bill Wendling wrote: > The 'struct fdtable' holds the file descriptor table information, > including the current file descriptor array 'fd' and its size 'max_fds'. > To harden the kernel against out-of-bounds accesses, we can annotate the > 'fd' pointer field with the '__counted_by_ptr' attribute, referencing > 'max_fds'. > > The compiler uses the '__counted_by_ptr' attribute to track the > size of the memory allocated for the pointer field, enabling > runtime bounds checks under KASAN and fortified functions. There are > three places where a 'struct fdtable' is initialized, and in all of > them, 'max_fds' is set before the 'fd' pointer is accessed or assigned > in all allocation and initialization places. > > No accesses to 'fd' occur before 'max_fds' is set, preventing any > potential runtime false-positives or panics due to uninitialized count > fields. > > Assisted-by: Gemini:3.1-pro-preview > Signed-off-by: Bill Wendling <[email protected]>
Looks good. Feel free to add: Reviewed-by: Jan Kara <[email protected]> Honza > --- > v3 - Add version to the PATCH subject line > --- > Cc: Alexander Viro <[email protected]> > Cc: Christian Brauner <[email protected]> > Cc: Jan Kara <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: "Gustavo A. R. Silva" <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > --- > include/linux/fdtable.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h > index c45306a9f007..3a5c88291125 100644 > --- a/include/linux/fdtable.h > +++ b/include/linux/fdtable.h > @@ -25,7 +25,7 @@ > > struct fdtable { > unsigned int max_fds; > - struct file __rcu **fd; /* current fd array */ > + struct file __rcu **fd __counted_by_ptr(max_fds); /* current fd > array */ > unsigned long *close_on_exec; > unsigned long *open_fds; > unsigned long *full_fds_bits; > -- > 2.55.0.897.gb25b4bd76c-goog > -- Jan Kara <[email protected]> SUSE Labs, CR
