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Commit b1af4315 authored by Phillip Lougher's avatar Phillip Lougher Committed by Linus Torvalds
Browse files

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: default avatarPhillip Lougher <phillip@lougher.demon.co.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent daeb6b6f

lib/decompress_bunzip2.c

+16 −6
Original line number Original line Diff line number Diff line
@@ -45,9 +45,11 @@ 
*/

*/









#ifndef STATIC

#ifdef STATIC

#define PREBOOT

#else

#include <linux/decompress/bunzip2.h>

#include <linux/decompress/bunzip2.h>

#endif /* !STATIC */

#endif /* STATIC */





#include <linux/decompress/mm.h>

#include <linux/decompress/mm.h>

#include <linux/slab.h>

#include <linux/slab.h>
@@ -681,9 +683,7 @@ STATIC int INIT bunzip2(unsigned char *buf, int len, 
	set_error_fn(error_fn);

	set_error_fn(error_fn);

	if (flush)

	if (flush)

		outbuf = malloc(BZIP2_IOBUF_SIZE);

		outbuf = malloc(BZIP2_IOBUF_SIZE);

	else



		len -= 4; /* Uncompressed size hack active in pre-boot

			     environment */

	if (!outbuf) {

	if (!outbuf) {

		error("Could not allocate output bufer");

		error("Could not allocate output bufer");

		return -1;

		return -1;
@@ -733,4 +733,14 @@ exit_0: 
	return i;

	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

lib/decompress_unlzma.c

+16 −5
Original line number Original line Diff line number Diff line
@@ -29,7 +29,9 @@ 
 *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

 */





#ifndef STATIC

#ifdef STATIC

#define PREBOOT

#else

#include <linux/decompress/unlzma.h>

#include <linux/decompress/unlzma.h>

#endif /* STATIC */

#endif /* STATIC */
@@ -543,9 +545,7 @@ STATIC inline int INIT unlzma(unsigned char *buf, int in_len, 
	int ret = -1;

	int ret = -1;





	set_error_fn(error_fn);

	set_error_fn(error_fn);

	if (!flush)



		in_len -= 4; /* Uncompressed size hack active in pre-boot

				environment */

	if (buf)

	if (buf)

		inbuf = buf;

		inbuf = buf;

	else

	else
@@ -645,4 +645,15 @@ exit_0: 
	return ret;

	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