Pkg xen devel - Jul 2015 - Bug#784880: [PATCH for-4.6] tools: libxl: Handle failure to create qemu dm logfile

If libxl_create_logfile fails for some reason then
libxl__create_qemu_logfile previously just carried on and dereferenced
the uninitialised logfile.

Check for the error from libxl_create_logfile, which has already
logged for us.

This was reported as Debian bug #784880.

Reported-by: Russell Coker <russell at coker.com.au>
Signed-off-by: Ian Campbell <ian.campbell at citrix.com>
Cc: 784880 at bugs.debian.org
---
Should be backported.
---
 tools/libxl/libxl_dm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index ad434f0..8ed2d2e 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -46,9 +46,11 @@ static const char *qemu_xen_path(libxl__gc *gc)
 static int libxl__create_qemu_logfile(libxl__gc *gc, char *name)
 {
     char *logfile;
-    int logfile_w;
+    int rc, logfile_w;
+
+    rc = libxl_create_logfile(CTX, name, &logfile);
+    if (rc) return rc;
 
-    libxl_create_logfile(CTX, name, &logfile);
     logfile_w = open(logfile, O_WRONLY|O_CREAT|O_APPEND, 0644);
     free(logfile);
 
-- 
2.1.4

On Mon, Jul 13, 2015 at 01:31:23PM +0100, Ian Campbell
wrote:
> If libxl_create_logfile fails for some reason then
> libxl__create_qemu_logfile previously just carried on and dereferenced
> the uninitialised logfile.
> 
> Check for the error from libxl_create_logfile, which has already
> logged for us.
> 
> This was reported as Debian bug #784880.
> 
> Reported-by: Russell Coker <russell at coker.com.au>
> Signed-off-by: Ian Campbell <ian.campbell at citrix.com>
> Cc: 784880 at bugs.debian.org
Acked-by: Wei Liu <wei.liu2 at citrix.com>
> ---
> Should be backported.
> ---
>  tools/libxl/libxl_dm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index ad434f0..8ed2d2e 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -46,9 +46,11 @@ static const char *qemu_xen_path(libxl__gc *gc)
>  static int libxl__create_qemu_logfile(libxl__gc *gc, char *name)
>  {
>      char *logfile;
> -    int logfile_w;
> +    int rc, logfile_w;
> +
> +    rc = libxl_create_logfile(CTX, name, &logfile);
> +    if (rc) return rc;
>  
> -    libxl_create_logfile(CTX, name, &logfile);
>      logfile_w = open(logfile, O_WRONLY|O_CREAT|O_APPEND, 0644);
>      free(logfile);
>  
> -- 
> 2.1.4

On Mon, 2015-07-13 at 14:07 +0100, Wei Liu wrote:
> On Mon, Jul 13, 2015 at 01:31:23PM +0100, Ian Campbell wrote:
> > If libxl_create_logfile fails for some reason then
> > libxl__create_qemu_logfile previously just carried on and dereferenced
> > the uninitialised logfile.
> > 
> > Check for the error from libxl_create_logfile, which has already
> > logged for us.
> > 
> > This was reported as Debian bug #784880.
> > 
> > Reported-by: Russell Coker <russell at coker.com.au>
> > Signed-off-by: Ian Campbell <ian.campbell at citrix.com>
> > Cc: 784880 at bugs.debian.org
> 
> Acked-by: Wei Liu <wei.liu2 at citrix.com>
Applied, thanks.

Ian, please: 
> > Should be backported.
> > ---
> >  tools/libxl/libxl_dm.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> > index ad434f0..8ed2d2e 100644
> > --- a/tools/libxl/libxl_dm.c
> > +++ b/tools/libxl/libxl_dm.c
> > @@ -46,9 +46,11 @@ static const char *qemu_xen_path(libxl__gc *gc)
> >  static int libxl__create_qemu_logfile(libxl__gc *gc, char *name)
> >  {
> >      char *logfile;
> > -    int logfile_w;
> > +    int rc, logfile_w;
> > +
> > +    rc = libxl_create_logfile(CTX, name, &logfile);
> > +    if (rc) return rc;
> >  
> > -    libxl_create_logfile(CTX, name, &logfile);
> >      logfile_w = open(logfile, O_WRONLY|O_CREAT|O_APPEND, 0644);
> >      free(logfile);
> >  
> > -- 
> > 2.1.4