mm: fix error handling for map_deny_write_exec

Commit 4a18419f ("mm/mprotect: use mmu_gather") changed 'goto out;' to
'break' in the loop.

This wasn't noticed while rebasing the MDWE patches, so fix it now.

Link: https://lkml.kernel.org/r/20230308190423.46491-3-joey.gouly@arm.com
Fixes: b507808e ("mm: implement memory-deny-write-execute as a prctl")
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Reported-by: Alexey Izbyshev <izbyshev@ispras.ru>
  Link: https://lore.kernel.org/linux-arm-kernel/8408d8901e9d7ee6b78db4c6cba04b78@ispras.ru/Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: nd <nd@arm.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mprotect.c

@@ -805,7 +805,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 
 		if (map_deny_write_exec(vma, newflags)) {
 			error = -EACCES;
-			goto out;
+			break;
 		}
 
 		/* Allow architectures to sanity-check the new flags */