Re: [Qemu-devel] [PATCH 1/9] Add API to manipulate dump_bitmap

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, May 07, 2013 at 10:14:11AM -0600, Eric Blake wrote:
> On 05/07/2013 01:16 AM, Qiao Nuohan wrote:
> > Struct dump_bitmap is associated with a tmp file, and the tmp file can be used
> > to save data of bitmap in kdump-compressed format temporarily.
> > The following patch will use these functions to get the data of bitmap and cache
> > them into tmp files.
> > 
> > Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
> > Reviewed-by: Zhang Xiaohe <zhangxh@cn.fujitsu.com>
> > ---
> 
> > +    db->file_name = (char *)g_malloc(strlen(filename) + strlen(tmpname) + 1);
> > +
> > +    strcpy(db->file_name, tmpname);
> > +    strcat(db->file_name, "/");
> > +    strcat(db->file_name, filename);
> 
> Off-by-one buffer overflow, since you forgot space for the NUL byte.  We
> use C, not C++, so you don't need to cast the result of g_malloc().

Using  g_strdup_printf("%s/%s", tmpname, filename); avoids the
allocation size problems entirely.

Daniel
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