On Mon, Nov 21, 2022 at 10:44:18AM +0800, Zhen Lei wrote:
> UBSAN: shift-out-of-bounds in fs/locks.c:2572:16
> left shift of 1 by 63 places cannot be represented in type 'long long int'
>
> Switch the calculation method to type_max() can help us eliminate this
> false positive.
>
> On the other hand, the old implementation has problems with char and
> short types, although not currently involved.
> printf("%d: %x\n", sizeof(char), INT_LIMIT(char));
> printf("%d: %x\n", sizeof(short), INT_LIMIT(short));
> 1: ffffff7f
> 2: ffff7fff
>
> Suggested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> ---
> include/linux/fs.h | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e654435f16512c1..a384741b1449457 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1131,9 +1131,8 @@ struct file_lock_context {
>
> /* The following constant reflects the upper bound of the file/locking space */
> #ifndef OFFSET_MAX
> -#define INT_LIMIT(x) (~((x)1 << (sizeof(x)*8 - 1)))
> -#define OFFSET_MAX INT_LIMIT(loff_t)
> -#define OFFT_OFFSET_MAX INT_LIMIT(off_t)
> +#define OFFSET_MAX type_max(loff_t)
> +#define OFFT_OFFSET_MAX type_max(off_t)
> #endif
>
> extern void send_sigio(struct fown_struct *fown, int fd, int band);
> --
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
- Eric
