On 28/07/2025 17:13, Richard Sandiford wrote:
Alfie Richards <alfie.richa...@arm.com> writes:
Hi,
Small fix to resolve an UBSAN diagnostic.
Reg tested for Aarch64
Thanks,
Alfie
-- >8 --
This adds a nullptr check to fix a regression where it is possible to call
`memcmp (NULL, NULL, 0)` which is UB.
This should fix the bootstrap-ubsan build.
gcc/ChangeLog:
PR middle-end/121261
* vec.h: Add null ptr check.
---
gcc/vec.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/gcc/vec.h b/gcc/vec.h
index 9604edb1c3c..1277a881f1c 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -2514,6 +2514,10 @@ public:
return false;
if (lhs.size () != rhs.size ())
return false;
+ /* Case where either is a NULL pointer and therefore, as both are valid,
+ both are empty slices with length 0. */
+ if (lhs.begin () == NULL || rhs.begin () == NULL)
+ return true;
It seems simpler (and IMO slightly clearer) to test for:
if (lhs.size () == 0)
return true;
Agreed, I wasn't certain this would satisfy UBSan but I have checked and
it does. Committed with this change.>
OK that way if you agree.
Thanks,
Richard
return memcmp (lhs.begin (), rhs.begin (), lhs.size ()) == 0;
}
