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Re: [PATCH] gelf_getauxv: Use memcpy instead of pointer dereference to avoid alignment problems.


On 08/25/2013 12:47 PM, Kurt Roeckx wrote:

> -      *dst = ((GElf_auxv_t *) data_scn->d.d_buf)[ndx];
> +      memcpy(dst, &((GElf_auxv_t *) data_scn->d.d_buf)[ndx], sizeof(*dst));

That's not correct, the cast is already undefined if the pointer lacks 
sufficient alignment.  GCC might even translate the latter into the former.

This might do it:

memcpy(dst, data_scn->d.d_buf + ndx * sizeof(GElf_auxv_t), 
sizeof(GElf_axuv_t));

(I hope there's a bounds check on ndx before that. :-)

-- 
Florian Weimer / Red Hat Product Security Team

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