>> (gdb) r test/evptests.txt
>> Starting program: /home/jwalton/openssl/test/evp_test test/evptests.txt
>> [Thread debugging using libthread_db enabled]
>> Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
>>
>> Program received signal SIGBUS, Bus error.
>> CRYPTO_ccm128_decrypt (ctx=ctx@entry=0x33788,
>> inp=inp@entry=0x33649
>> "\232_\314ʹ\317\004\347)='u\314v\244\210\360B8-\224\233C\267ֻ+\230dxg&",
>> out=<optimized out>,
>> out@entry=0x335d8
>> "\004\065\331v\004\065\331v)='u\314v\244\210\360B8-\224\233C\267ֻ+\230dxg&",
>> len=len@entry=0x20) at crypto/modes/ccm128.c:253
>> 253 ctx->cmac.u[0] ^= (scratch.u[0] ^= temp.u[0]);
>> (gdb)
>
> This line is within #if defined(STRICT_ALIGNMENT), which means that
> compiler is responsible for aligning data, and SIGBUS means that it
> failed. And indeed, looking at disassembler output it crashes in vld1.64
> {d16-d17}, [r6 :64], instruction that requires 64-bit alignment. So
> compiler generated the instruction, but didn't care to ensure the
> alignment. There is no other conclusion one can draw but that is indeed
> a compiler bug. Besides, default ./config works just fine and (once
> again) I see no compelling reason for not using it.
I think these are the lines:
#if defined(STRICT_ALIGNMENT)
union {
u64 u[2];
u8 c[16];
} temp;
#endif
...
#if defined(STRICT_ALIGNMENT)
memcpy(temp.c, inp, 16);
ctx->cmac.u[0] ^= (scratch.u[0] ^= temp.u[0]);
ctx->cmac.u[1] ^= (scratch.u[1] ^= temp.u[1]);
...
#endif
I *thought* accessing a union member through its inactive member is
undefined behavior. Once 'scratch.c' and 'temp.c' were used, using
'temp.c' and 'temp.u' leads to the UB.
Maybe my wires are crossed somewhere....
Jeff
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