Hello,
I've spent some time looking at it today (after Christian kindly
provided access to gnunet's sparc buildbot and detailed instructions
on how to reproduce the bug), and by now I'm pretty certain that the
unaligned memory accesses are caused by a bug in gnunet. At first
glance it looks like the GNUNET_HashCode struct should always be
word-aligned, however closer inspection reveals that its definition
(in src/include/gnunet_common.h) looks like this:
GNUNET_NETWORK_STRUCT_BEGIN
[...]
/**
* @brief 512-bit hashcode
*/
struct GNUNET_HashCode
{
uint32_t bits[512 / 8 / sizeof (uint32_t)]; /* = 16 */
};
[...]
GNUNET_NETWORK_STRUCT_END
The preprocessed source indicates that these header and footer macros
expand into
#pragma pack(push)
#pragma pack(1)
and
#pragma pack(pop)
respectively. This essentially eliminates the alignment requirements
for members of this struct, so compiler is fully within its right to
place it at 2-bytes boundary, which eventually leads to an unaligned
memory access resulting in a crash.
Best regards,
--
Jurij Smakov ju...@wooyd.org
Key: http://www.wooyd.org/pgpkey/ KeyID: C99E03CC
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