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bzip2/lzma: remove nasty uncompressed size hack in pre-boot environment 

decompress_bunzip2 and decompress_unlzma have a nasty hack that subtracts
4 from the input length if being called in the pre-boot environment.

This is a nasty hack because it relies on the fact that flush = NULL only
when called from the pre-boot environment (i.e.
arch/x86/boot/compressed/misc.c).  initramfs.c/do_mounts_rd.c pass in a
flush buffer (flush != NULL).

This hack prevents the decompressors from being used with flush = NULL by
other callers unless knowledge of the hack is propagated to them.

This patch removes the hack by making decompress (called only from the
pre-boot environment) a wrapper function that subtracts 4 from the input
length before calling the decompressor.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Phillip Lougher 2009-08-06 15:09:31 -07:00 committed by Linus Torvalds
parent daeb6b6fbe
commit b1af4315d8
2 changed files with 32 additions and 11 deletions
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22
lib/decompress_bunzip2.c
View File

@ -45,9 +45,11 @@
*/
#ifndef STATIC
#ifdef STATIC
#define PREBOOT
#else
#include <linux/decompress/bunzip2.h>
#endif /* !STATIC */
#endif /* STATIC */
#include <linux/decompress/mm.h>
#include <linux/slab.h>
@ -681,9 +683,7 @@ STATIC int INIT bunzip2(unsigned char *buf, int len,
set_error_fn(error_fn);
if (flush)
outbuf = malloc(BZIP2_IOBUF_SIZE);
else
len -= 4; /* Uncompressed size hack active in pre-boot
environment */
if (!outbuf) {
error("Could not allocate output bufer");
return -1;
@ -733,4 +733,14 @@ exit_0:
return i;
}
#define decompress bunzip2
#ifdef PREBOOT
STATIC int INIT decompress(unsigned char *buf, int len,
int(*fill)(void*, unsigned int),
int(*flush)(void*, unsigned int),
unsigned char *outbuf,
int *pos,
void(*error_fn)(char *x))
{
return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error_fn);
}
#endif

21
lib/decompress_unlzma.c
View File

@ -29,7 +29,9 @@
*Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef STATIC
#ifdef STATIC
#define PREBOOT
#else
#include <linux/decompress/unlzma.h>
#endif /* STATIC */
@ -543,9 +545,7 @@ STATIC inline int INIT unlzma(unsigned char *buf, int in_len,
int ret = -1;
set_error_fn(error_fn);
if (!flush)
in_len -= 4; /* Uncompressed size hack active in pre-boot
environment */
if (buf)
inbuf = buf;
else
@ -645,4 +645,15 @@ exit_0:
return ret;
}
#define decompress unlzma
#ifdef PREBOOT
STATIC int INIT decompress(unsigned char *buf, int in_len,
int(*fill)(void*, unsigned int),
int(*flush)(void*, unsigned int),
unsigned char *output,
int *posp,
void(*error_fn)(char *x)
)
{
return unlzma(buf, in_len - 4, fill, flush, output, posp, error_fn);
}
#endif