[PATCH] xc_inflate_buffer fix

[PATCH] xc_inflate_buffer fix

[David Lively]

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Hi -
   I notice some of my initrds are failing to gunzip:
ERROR: inflate failed, sts -5
   These same initrds work fine with Ben Thomas' original
patch introducing xc_{linux,hvm}_build_mem.  The checked-in
version changed some declarations from unsigned char * to
char *, breaking the output length computation in xc_inflate_buffer.
   This patch assumes you want to keep using the signed char *
for the interface, so it simply inserts a few casts to unsigned.
Tested lightly, but the bug is pretty obvious once you notice
the signedness change ...

Dave


[-- Attachment #2: xc-inflate-buffer-fix.patch --]
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diff -r 1d741a415927 tools/libxc/xg_private.c
--- a/tools/libxc/xg_private.c	Wed Mar 15 11:48:33 2006 -0500
+++ b/tools/libxc/xg_private.c	Wed Mar 15 12:28:05 2006 -0500
@@ -77,10 +77,11 @@ char *xc_inflate_buffer(const char *in_b
         return (char *)in_buf;
     }
 
-    out_len = in_buf[in_size-4] +
-        (256 * (in_buf[in_size-3] +
-                (256 * (in_buf[in_size-2] +
-                        (256 * in_buf[in_size-1])))));
+    out_len = (unsigned char)in_buf[in_size-4] +
+        (256 * ((unsigned char)in_buf[in_size-3] +
+                (256 * ((unsigned char)in_buf[in_size-2] +
+                        (256 * (unsigned char)in_buf[in_size-1])))));
+
     bzero(&zStream, sizeof(zStream));
     out_buf = malloc(out_len + 16);        /* Leave a little extra space */
     if ( out_buf == NULL )

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Re: [PATCH] xc_inflate_buffer fix

[David Lively]

Oops, forgot:

Signed-off-by: David Lively <dlively@virtualiron.com>

Dave

David Lively wrote:
> Hi -
>   I notice some of my initrds are failing to gunzip:
> ERROR: inflate failed, sts -5
>   These same initrds work fine with Ben Thomas' original
> patch introducing xc_{linux,hvm}_build_mem.  The checked-in
> version changed some declarations from unsigned char * to
> char *, breaking the output length computation in xc_inflate_buffer.
>   This patch assumes you want to keep using the signed char *
> for the interface, so it simply inserts a few casts to unsigned.
> Tested lightly, but the bug is pretty obvious once you notice
> the signedness change ...
> 
> Dave
> 
> 
> ------------------------------------------------------------------------
> 
> diff -r 1d741a415927 tools/libxc/xg_private.c
> --- a/tools/libxc/xg_private.c	Wed Mar 15 11:48:33 2006 -0500
> +++ b/tools/libxc/xg_private.c	Wed Mar 15 12:28:05 2006 -0500
> @@ -77,10 +77,11 @@ char *xc_inflate_buffer(const char *in_b
>          return (char *)in_buf;
>      }
>  
> -    out_len = in_buf[in_size-4] +
> -        (256 * (in_buf[in_size-3] +
> -                (256 * (in_buf[in_size-2] +
> -                        (256 * in_buf[in_size-1])))));
> +    out_len = (unsigned char)in_buf[in_size-4] +
> +        (256 * ((unsigned char)in_buf[in_size-3] +
> +                (256 * ((unsigned char)in_buf[in_size-2] +
> +                        (256 * (unsigned char)in_buf[in_size-1])))));
> +
>      bzero(&zStream, sizeof(zStream));
>      out_buf = malloc(out_len + 16);        /* Leave a little extra space */
>      if ( out_buf == NULL )

Re: [PATCH] xc_inflate_buffer fix

[Keir Fraser]

On 15 Mar 2006, at 17:56, David Lively wrote:

>   I notice some of my initrds are failing to gunzip:
> ERROR: inflate failed, sts -5
>   These same initrds work fine with Ben Thomas' original
> patch introducing xc_{linux,hvm}_build_mem.  The checked-in
> version changed some declarations from unsigned char * to
> char *, breaking the output length computation in xc_inflate_buffer.
>   This patch assumes you want to keep using the signed char *
> for the interface, so it simply inserts a few casts to unsigned.
> Tested lightly, but the bug is pretty obvious once you notice
> the signedness change ...

Yep, my bad. Thanks.

  -- Keir