On 7/9/24 7:12PM, Remington Brasga wrote:
> Fix issue with UBSAN throwing shift-out-of-bounds warning.
>
> Reported-by: syzbot+e38d703eeb410b17b473@syzkaller.appspotmail.com
> Signed-off-by: Remington Brasga <rbrasga@uci.edu>
> ---
> When nb = 32, `mask = mask >> nb` or shorthand `mask >>= nb` throws
> shift-out-of-bounds warning.
> `mask = (mask >> nb)` removes that warning.
Looks good. Applied.
Shaggy
>
> Link to the syzbot bug report: https://lore.kernel.org/all/0000000000006fc563061cbc7f9c@google.com/T/
>
> fs/jfs/jfs_dmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index cb3cda1390ad..636aae946e84 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -3020,7 +3020,7 @@ static int dbFindBits(u32 word, int l2nb)
>
> /* scan the word for nb free bits at nb alignments.
> */
> - for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
> + for (bitno = 0; mask != 0; bitno += nb, mask = (mask >> nb)) {
> if ((mask & word) == mask)
> break;
> }