crypto/mem.c: don't use aligned_alloc in CRYPTO_aligned_alloc

The original C11 specification is pretty weird: it specifies that the size
must be a multiple of alignment (rendering it useless for small page-aligned
allocations that, for example, might be useful for RDMA) and until DR460[1]
it was UB in failing to do so (as it is with OPENSSL_ligned_alloc() calls
in alloc_new_neighborhood_list() on 32-bit systems, for example).
Moreover, it has arguably not been used much before, as all supported POSIX
systems have at least POSIX 2001 compatibility level nowadays,
Windows doesn't implement aligned_alloc() at all (because implementation
of free() in MS CRT is unable to handle aligned allocations[2]),
and _ISOC11_SOURCE is a glibc-specific feature test macro.

[1] https://open-std.org/JTC1/SC22/WG14/www/docs/summary.htm#dr_460
[2] https://learn.microsoft.com/en-us/cpp/standard-library/cstdlib?view=msvc-170#remarks-6

Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28059)

diff --git a/crypto/mem.c b/crypto/mem.c
index 161d61dae6365beb6ef79a80359d3269f83c8b94..3ac848417654caa68d5dc61c05cba64c9d6e6d90 100644 (file)
--- a/crypto/mem.c
+++ b/crypto/mem.c
@@ -246,9 +246,6 @@ void *CRYPTO_aligned_alloc(size_t num, size_t alignment, void **freeptr,
             return NULL;
         *freeptr = ret;
         return ret;
-#elif defined(_ISOC11_SOURCE)
-        ret = *freeptr = aligned_alloc(alignment, num);
-        return ret;
 #endif
     }