[gdb/exp] Fix UB in scalar_binop

When building gdb with -fsanitize=undefined, I run into:
...
$ gdb -q -batch -ex "p -(-0x7fffffffffffffff - 1)"
src/gdb/valarith.c:1385:10: runtime error: signed integer overflow: \
  0 - -9223372036854775808 cannot be represented in type 'long int'
$1 = -9223372036854775808
...

Fix this by performing the substraction in scalar_binop using unsigned types.

Tested on x86_64-linux.
This commit is contained in:
Tom de Vries
2022-05-23 14:50:02 +02:00
parent 05527d8ca1
commit 5a3cf18c2e
2 changed files with 6 additions and 1 deletions

View File

@ -1382,7 +1382,10 @@ scalar_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
break;
case BINOP_SUB:
v = v1 - v2;
/* Avoid runtime error: signed integer overflow: \
0 - -9223372036854775808 cannot be represented in type
'long int'. */
v = (ULONGEST)v1 - (ULONGEST)v2;
break;
case BINOP_MUL: