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Re: [PATCH] elf: dl-minimal malloc needs to respect fundamental alignment

On 06/21/2016 02:54 PM, H.J. Lu wrote:
On Tue, Jun 21, 2016 at 4:17 AM, Florian Weimer <> wrote:
If malloc is used instead of memalign for small alignments,
malloc needs to provide the ABI-required alignment.

2016-06-21  Florian Weimer  <>

        * elf/dl-minimal.c (malloc): Allocate with fundamental alignment.

diff --git a/elf/dl-minimal.c b/elf/dl-minimal.c
index c8a8f8d..2d7d139 100644
--- a/elf/dl-minimal.c
+++ b/elf/dl-minimal.c
@@ -27,6 +27,7 @@
 #include <sys/types.h>
 #include <ldsodefs.h>
 #include <_itoa.h>
+#include <stdalign.h>

 #include <assert.h>

@@ -90,7 +91,7 @@ __libc_memalign (size_t align, size_t n)
 void * weak_function
 malloc (size_t n)
-  return __libc_memalign (sizeof (double), n);
+  return __libc_memalign (_Alignof (max_align_t), n);

 /* We use this function occasionally since the real implementation may

We also have MALLOC_ALIGNMENT in malloc.  Should they be consistent?

MALLOC_ALIGNMENT is potentially larger. malloc/tst-malloc-thread-fail tests for alignment. To my knowledge, it passes on all regularly tested architectures after commit dea39b13e2958a7f0e75b5594a06d97d61cc439f.


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