On Wed, Aug 30, 2023 at 4:46 PM Philipp Stanner <pstanner@xxxxxxxxxx> wrote: > > Currently, user array duplications are sometimes done without an > overflow check. Sometimes the checks are done manually; sometimes the > array size is calculated with array_size() and sometimes by calculating > n * size directly in code. > > Introduce wrappers for arrays for memdup_user() and vmemdup_user() to > provide a standardized and safe way for duplicating user arrays. > > This is both for new code as well as replacing usage of (v)memdup_user() > in existing code that uses, e.g., n * size to calculate array sizes. ... > --- a/include/linux/string.h > +++ b/include/linux/string.h I'm wondering if this has no side-effects as string.h/string.c IIRC is used also for early stages where some of the APIs are not available. > @@ -6,6 +6,8 @@ > #include <linux/types.h> /* for size_t */ > #include <linux/stddef.h> /* for NULL */ > #include <linux/errno.h> /* for E2BIG */ > +#include <linux/overflow.h> /* for check_mul_overflow() */ > +#include <linux/err.h> /* for ERR_PTR() */ Can we preserve order (to some extent)? > #include <linux/stdarg.h> > #include <uapi/linux/string.h> ... > +/** > + * memdup_array_user - duplicate array from user space > + * Do we need this blank line? > + * @src: source address in user space > + * @n: number of array members to copy > + * @size: size of one array member > + * > + * Return: an ERR_PTR() on failure. Result is physically > + * contiguous, to be freed by kfree(). > + */ ... > +/** > + * vmemdup_array_user - duplicate array from user space > + * Redundant? > + * @src: source address in user space > + * @n: number of array members to copy > + * @size: size of one array member > + * > + * Return: an ERR_PTR() on failure. Result may be not > + * physically contiguous. Use kvfree() to free. > + */ -- With Best Regards, Andy Shevchenko
