Re: [Xen-devel] [PATCH v4 5/6] microcode: delete microcode pointer and size from microcode_info

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Nov 28, 2018 at 01:34:15PM +0800, Chao Gao wrote:
> Microcode pointer and size is passed to other cpu to parse microcode
> locally. Now, parsing microcode is done on one CPU. Others just
> find a suitable microcode stored in microcode_cache.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> ---
>  xen/arch/x86/microcode.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/x86/microcode.c b/xen/arch/x86/microcode.c
> index cca7b2c..0b435f4 100644
> --- a/xen/arch/x86/microcode.c
> +++ b/xen/arch/x86/microcode.c
> @@ -190,9 +190,7 @@ DEFINE_PER_CPU(struct ucode_cpu_info, ucode_cpu_info);
>  
>  struct microcode_info {
>      unsigned int cpu;
> -    uint32_t buffer_size;
>      int error;
> -    char buffer[1];
>  };
>  
>  static void __microcode_fini_cpu(unsigned int cpu)
> @@ -270,6 +268,7 @@ int microcode_update(XEN_GUEST_HANDLE_PARAM(const_void) 
> buf, unsigned long len)
>      struct microcode_info *info;
>      unsigned int cpu = smp_processor_id();
>      struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
> +    void * buffer;
>  
>      if ( len != (uint32_t)len )
>          return -E2BIG;
> @@ -277,11 +276,12 @@ int microcode_update(XEN_GUEST_HANDLE_PARAM(const_void) 
> buf, unsigned long len)
>      if ( microcode_ops == NULL )
>          return -EINVAL;
>  
> -    info = xmalloc_bytes(sizeof(*info) + len);
> -    if ( info == NULL )
> +    info = xmalloc(struct microcode_info);
> +    buffer = xmalloc_bytes(len);
> +    if ( !info || !buffer )

You are again likely to leak memory with this construct.

Roger.

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