Re: [Qemu-devel] [PATCH] migration: fix bad string passed to error_report()

[Eric Blake <eblake@redhat.com>]

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On 02/04/2016 02:20 AM, Greg Kurz wrote:
> state->name does not contain a terminating '\0' and you may get:
> 
> Machine type received is 'pseries-2.3y�?' and local is 'pseries-2.4'
> load of migration failed: Invalid argument
> 
> Let's add a precision modifier to fix this.
> 
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> ---
>  migration/savevm.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 954988d12130..3335cc23175c 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -299,8 +299,8 @@ static int configuration_post_load(void *opaque, int version_id)
>      const char *current_name = MACHINE_GET_CLASS(current_machine)->name;
>  
>      if (strncmp(state->name, current_name, state->len) != 0) {
> -        error_report("Machine type received is '%s' and local is '%s'",
> -                     state->name, current_name);
> +        error_report("Machine type received is '%.*s' and local is '%s'",
> +                     state->len, state->name, current_name);

.* required an 'int', but SaveState.len is uint32_t.  There are
platforms (hello, 32-bit cygwin) where uint32_t is a long, and where
this would therefore cause a compiler warning.  You'll be safer with an
explicit cast, '(int) state->len'.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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