Re: [PATCH v2] disas: sparc: Fix integer overflow in compare_opcodes() for loop

Hi Christian,

On 3/6/26 21:04, Christian Barry wrote:
> From: Christian Barry <[email protected]>
> 
> Replaced left-shift of a literal 1 by i inside of two for loops in compare_opcodes() with 1ul type qualifier. This makes it so 1 is explicitly interpreted as an unsigned long int, preventing overflows.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/2618
> 
> Signed-off-by: Christian Barry <[email protected]>
> Co-developed-by: Eduardo Augusto Cavalcanti <[email protected]>
> Signed-off-by: Eduardo Augusto Cavalcanti <[email protected]>
> ---
>   disas/sparc.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/disas/sparc.c b/disas/sparc.c
> index 5689533ce1..40c1164554 100644
> --- a/disas/sparc.c
> +++ b/disas/sparc.c
> @@ -2515,7 +2515,7 @@ compare_opcodes (const void * a, const void * b)
>        another, it is important to order the opcodes in the right order.  */
>     for (i = 0; i < 32; ++i)
>       {
> -      unsigned long int x = 1 << i;
> +      unsigned long int x = 1ul << i;
>         int x0 = (match0 & x) != 0;
>         int x1 = (match1 & x) != 0;

As Artyom suggested we should cherry-pick binutils commit 4383e1fc3b326.

Alternatively:

   if (match0 != match1) {
       return extract32(match1, clz32(match0 ^ match1), 1) ?: -1;
   }