linux-kernel - [PATCH] initrd: Fix lz4 decompress with initrd

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Date:	Fri, 20 Jun 2014 19:30:09 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Cc:	Kyungsik Lee <kyungsik.lee@....com>,
	Jan Beulich <JBeulich@...e.com>, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH] initrd: Fix lz4 decompress with initrd

During testing initrd (>2G) support, find decompress/lz4 does
not work with initrd at all.

decompress_* should support:
1. inbuf[]/outbuf[] for kernel preboot.
2. inbuf[]/flush() for initramfs
3. fill()/flush() for initrd.

in the unlz4 does not handle case 3, as input len is passed
as 0, and it failed in first try.

Fix that add one extra if (fill) checking, and get out if
EOF from the fill().

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 lib/decompress_unlz4.c |   65 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 43 insertions(+), 22 deletions(-)

Index: linux-2.6/lib/decompress_unlz4.c
===================================================================
--- linux-2.6.orig/lib/decompress_unlz4.c
+++ linux-2.6/lib/decompress_unlz4.c
@@ -83,13 +83,20 @@ STATIC inline int INIT unlz4(u8 *input,
 	if (posp)
 		*posp = 0;
 
-	if (fill)
-		fill(inp, 4);
+	if (fill) {
+		size = fill(inp, 4);
+		if (size < 4) {
+			error("data corrupted");
+			goto exit_2;
+		}
+	}
 
 	chunksize = get_unaligned_le32(inp);
 	if (chunksize == ARCHIVE_MAGICNUMBER) {
-		inp += 4;
-		size -= 4;
+		if (!fill) {
+			inp += 4;
+			size -= 4;
+		}
 	} else {
 		error("invalid header");
 		goto exit_2;
@@ -100,29 +107,44 @@ STATIC inline int INIT unlz4(u8 *input,
 
 	for (;;) {
 
-		if (fill)
-			fill(inp, 4);
+		if (fill) {
+			size = fill(inp, 4);
+			if (size == 0)
+				break;
+			if (size < 4) {
+				error("data corrupted");
+				goto exit_2;
+			}
+		}
 
 		chunksize = get_unaligned_le32(inp);
 		if (chunksize == ARCHIVE_MAGICNUMBER) {
-			inp += 4;
-			size -= 4;
+			if (!fill) {
+				inp += 4;
+				size -= 4;
+			}
 			if (posp)
 				*posp += 4;
 			continue;
 		}
-		inp += 4;
-		size -= 4;
+
 
 		if (posp)
 			*posp += 4;
 
-		if (fill) {
+		if (!fill) {
+			inp += 4;
+			size -= 4;
+		} else {
 			if (chunksize > lz4_compressbound(uncomp_chunksize)) {
 				error("chunk length is longer than allocated");
 				goto exit_2;
 			}
-			fill(inp, chunksize);
+			size = fill(inp, chunksize);
+			if (size < chunksize) {
+				error("data corrupted");
+				goto exit_2;
+			}
 		}
 #ifdef PREBOOT
 		if (out_len >= uncomp_chunksize) {
@@ -149,18 +171,17 @@ STATIC inline int INIT unlz4(u8 *input,
 		if (posp)
 			*posp += chunksize;
 
-		size -= chunksize;
+		if (!fill) {
+			size -= chunksize;
 
-		if (size == 0)
-			break;
-		else if (size < 0) {
-			error("data corrupted");
-			goto exit_2;
+			if (size == 0)
+				break;
+			else if (size < 0) {
+				error("data corrupted");
+				goto exit_2;
+			}
+			inp += chunksize;
 		}
-
-		inp += chunksize;
-		if (fill)
-			inp = inp_start;
 	}
 
 	ret = 0;
--
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