Re: [Qemu-devel] [PATCH] fix loading tiny kernels

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

On Tue, Feb 03, 2009 at 10:06:10AM +0100, Ren? Rebe wrote:
> I babbled:
> >Further testing / polishing the multi-boot kernel loading support I found
> >the existing code fails to load unusual small kernels, less than 8192 
> >bytes -
> >for example the example multi-boot kernel shipped within GRUB that
> >compiles to just 7121 bytes on my system.
> >
> >Signed-off-by: René Rebe <rene@exactcode.de>
> >
> >--- hw/pc.c     (revision 6501)
> >+++ hw/pc.c     (working copy)
> >@@ -554,7 +989,7 @@
> >    /* load the kernel header */
> >    f = fopen(kernel_filename, "rb");
> >    if (!f || !(kernel_size = get_file_size(f)) ||
> >-    fread(header, 1, 1024, f) != 1024) {
> >+    fread(header, 1, MIN(8192, kernel_size), f) != MIN(8192, 
> >kernel_size)) {
> >    fprintf(stderr, "qemu: could not load kernel '%s'\n",
> >        kernel_filename);
> >    exit(1);
> >
> Ah,  sorry - mix in the series. This only applies to the multi-boot series
> which increases the header read to 8192 bytes.

Regardless, this code should not hardcode the size like this. It should
use sizeof(header) instead of 1024 or 8192, thus avoiding the potential
bug.

Regards,
Daniel
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