[Crash-utility] [PATCH 1/2] qemu: parse 'vm_configuration' section

[Dr. David Alan Gilbert]

* Pankaj Gupta (pagupta at redhat.com) wrote:
>  Teach crash to parse 'QEMU_VM_CONFIGURATION' section. This
>  section is added by migration code to save VM running state.
> 
> Signed-off-by: Pankaj Gupta <pagupta at redhat.com>
> ---
>  qemu-load.c | 16 ++++++++++++++++
>  qemu-load.h |  3 ++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/qemu-load.c b/qemu-load.c
> index 8b4372e..7ee58a3 100644
> --- a/qemu-load.c
> +++ b/qemu-load.c
> @@ -208,6 +208,16 @@ get_string (FILE *fp, char *name)
>  	name[sz] = 0;
>  	return sz;
>  }
> +static int
> +get_string_len (FILE *fp, char *name, uint32_t sz)
> +{
> +	size_t items ATTRIBUTE_UNUSED;
> +	if (sz == EOF)
> +		return -1;
> +	items = fread (name, sz, 1, fp);
> +	name[sz] = 0;
> +	return sz;
> +}
>  
>  static void
>  ram_read_blocks (FILE *fp, uint64_t size)
> @@ -924,6 +934,7 @@ qemu_load (const struct qemu_device_loader *devices, uint32_t required_features,
>  	struct qemu_device_list *result = NULL;
>  	struct qemu_device *last = NULL;;
>  	size_t items ATTRIBUTE_UNUSED;
> +	char name[257];
>  
>  	switch (get_be32 (fp)) {
>  	case QEMU_VM_FILE_MAGIC:
> @@ -961,6 +972,11 @@ qemu_load (const struct qemu_device_loader *devices, uint32_t required_features,
>  			break;
>  		if (sec == QEMU_VM_EOF)
>  			break;
> +		if (sec == QEMU_VM_CONFIGURATION) {
> +			uint32_t len = get_be32 (fp);
> +			get_string_len (fp, name, len);
> +			continue;
> +                }

Be careful about buffer over runs!   That 'len' must be checked to ensure
it fits into 'name' - or dynamically allocate 'name'. OK, in practice the value
will be small, but this tool is aimed to read crash files that might have been
dumped by a customer and so you have to treat the contents of the file
as potentially hostile, either due to file corruption or really someone trying
to be nasty.

Dave

>  		d = device_get (devices, result, sec, fp);
>  		if (!d)
> diff --git a/qemu-load.h b/qemu-load.h
> index e52b068..d5b2078 100644
> --- a/qemu-load.h
> +++ b/qemu-load.h
> @@ -29,7 +29,8 @@ enum qemu_save_section {
>    QEMU_VM_SECTION_PART,
>    QEMU_VM_SECTION_END,
>    QEMU_VM_SECTION_FULL,
> -  QEMU_VM_SUBSECTION
> +  QEMU_VM_SUBSECTION,
> +  QEMU_VM_CONFIGURATION = 0x07
>  };
>  
>  enum qemu_features {
> -- 
> 1.9.3
> 
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK