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From: "muecker at gwdg dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug sanitizer/98623] New: sanitizer does not diagnose when passing
 pointers to arrays of incorrect run-time length
Date: Mon, 11 Jan 2021 16:20:16 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98623

            Bug ID: 98623
           Summary: sanitizer does not diagnose when passing pointers to
                    arrays of incorrect run-time length
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: muecker at gwdg dot de
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxi=
n at gcc dot gnu.org
  Target Milestone: ---

In the following example, there is no run-time error with -fsanitize=3Dunde=
fined
although the pointer types for the second argument are required to point to
compatible types and it is UB when variably modified types have non-matching
lengths when they are required to be compatible (6.7.6.2p6). From a practic=
al
point of view, this would very desirable as it would close the last loop-ho=
le
that prevents one from having proper bounds checking when using pointers to
VLAs.

(In this case, but not in general, it should also be possible to emit an er=
ror
at compile time.)


extern void f(int n, double (*x)[n]);

int main()
{
        double a[10];
        f(9, &a);
}=