[PATCH v2 0/6] crash: Bundle of fixes for Xen

Dave Anderson anderson at redhat.com
Tue Aug 14 10:04:00 EDT 2012

----- Original Message -----
> On Mon, Aug 13, 2012 at 03:16:53PM -0400, Dave Anderson wrote:
> [...]
> > OK good.  It tests OK on a few older pvops kernels that I have on
> > hand.
> >
> > The only thing I've changed is to handle compiler warnings in x86_64.c and
> > x86.c by initializing p2m_top to NULL in x86_64_pvops_xendump_p2m_l3_create()
> > and x86_pvops_xendump_p2m_l3_create().  I also used GETBUF() in those two
> > functions to avoid having to add the malloc-failure line.
> No problem. However, I am a bit surprised that you have seen some warnings.
> I have not seen any. Did you compiled crash with extra options or something
> like that? Or maybe there is a diffrence in our compilers (mine is gcc version
>  4.1.2 20061115 (prerelease) (Debian 4.1.1-21) - quite ancient).

Extra options (also with gcc 4.1.2) -- try building with "make warn".  It adds:

 WARNING_OPTIONS=-Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector

or "make Warn", which adds -Werror to the above.

In those two functions there are "goto err" statements prior to allocating
p2m_top, and so the free(p2m_top) could receive a random stack value.  Of
course even if it did get by the free() call in that highly unlikely case,
the crash session is just about to fatally shut itself down.


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