[PATCH] IBM zSystems: Fix left-shifting negative PCRel32 values (PR gas/29152)
Andreas Krebbel
krebbel@linux.ibm.com
Mon May 16 20:01:04 GMT 2022
On 5/16/22 20:35, Ilya Leoshkevich wrote:
> s390_insert_operand ()'s val, min and max are encoded PCRel32 values
> and need to be left-shifted by 1 before being shown to the user.
> Left-shifting negative values is undefined behavior in C, but the
> current code does not try to prevent it, causing UBSan to complain.
>
> Fix by casting the values to their unsigned equivalents before
> shifting.
> ---
> gas/config/tc-s390.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/gas/config/tc-s390.c b/gas/config/tc-s390.c
> index fb452f8a986..04a3c059c91 100644
> --- a/gas/config/tc-s390.c
> +++ b/gas/config/tc-s390.c
> @@ -622,9 +622,9 @@ s390_insert_operand (unsigned char *insn,
>
> if (operand->flags & S390_OPERAND_PCREL)
> {
> - val <<= 1;
> - min <<= 1;
> - max <<= 1;
> + val = (offsetT) ((addressT) val << 1);
> + min = (offsetT) ((addressT) min << 1);
> + max = (offsetT) ((addressT) max << 1);
> }
> if (file == (char *) NULL)
> as_bad (err, (int64_t) val, (int64_t) min, (int64_t) max);
Committed to master. Thanks!
Andreas
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