Re: [Xen-devel] [PATCH v2 for-4.9 2/7] tools/insn-fuzz: Don't hit memcpy() for zero-length reads

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.04.17 at 19:53, <andrew.cooper3@xxxxxxxxxx> wrote:
> For control-flow changes, the emulator needs to perform a zero-length
> instruction fetch at the target offset.  It also passes NULL for the
> destination buffer, as there is no instruction stream to collect.
> 
> This trips up UBSAN when passed to memcpy(), as passing NULL is undefined
> behaviour per the C spec (irrespective of passing a size of 0).
> 
> Special case these fetches in fuzz_insn_fetch() before reaching data_read().
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>



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