lib/decompressors: use real out buf size for gunzip with kernel

When loading x86 64bit kernel above 4GiB with patched grub2, got kernel
gunzip error.

| early console in decompress_kernel
| decompress_kernel:
|       input: [0x807f2143b4-0x807ff61aee]
|      output: [0x807cc00000-0x807f3ea29b] 0x027ea29c: output_len
| boot via startup_64
| KASLR using RDTSC...
|  new output: [0x46fe000000-0x470138cfff] 0x0338d000: output_run_size
|  decompress: [0x46fe000000-0x47007ea29b] <=== [0x807f2143b4-0x807ff61aee]
|
| Decompressing Linux... gz...
|
| uncompression error
|
| -- System halted

the new buffer is at 0x46fe000000ULL, decompressor_gzip is using
0xffffffb901ffffff as out_len.  gunzip in lib/zlib_inflate/inflate.c cap
that len to 0x01ffffff and decompress fails later.

We could hit this problem with crashkernel booting that uses kexec loading
kernel above 4GiB.

We have decompress_* support:
    1. inbuf[]/outbuf[] for kernel preboot.
    2. inbuf[]/flush() for initramfs
    3. fill()/flush() for initrd.
This bug only affect kernel preboot path that use outbuf[].

Add __decompress and take real out_buf_len for gunzip instead of guessing
wrong buf size.

Fixes: 1431574a1c4 (lib/decompressors: fix "no limit" output buffer length)
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Jon Medhurst <tixy@linaro.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 5 deletions

diff --git a/lib/decompress_inflate.c b/lib/decompress_inflate.c
index d4c7891..555c06b 100644
--- a/lib/decompress_inflate.c
+++ b/lib/decompress_inflate.c
@@ -1,4 +1,5 @@
 #ifdef STATIC
+#define PREBOOT
 /* Pre-boot environment: included */
 
 /* prevent inclusion of _LINUX_KERNEL_H in pre-boot environment: lots
@@ -33,23 +34,23 @@ static long INIT nofill(void *buffer, unsigned long len)
 }
 
 /* Included from initramfs et al code */
-STATIC int INIT gunzip(unsigned char *buf, long len,
+STATIC int INIT __gunzip(unsigned char *buf, long len,
 		       long (*fill)(void*, unsigned long),
 		       long (*flush)(void*, unsigned long),
-		       unsigned char *out_buf,
+		       unsigned char *out_buf, long out_len,
 		       long *pos,
 		       void(*error)(char *x)) {
 	u8 *zbuf;
 	struct z_stream_s *strm;
 	int rc;
-	size_t out_len;
 
 	rc = -1;
 	if (flush) {
 		out_len = 0x8000; /* 32 K */
 		out_buf = malloc(out_len);
 	} else {
-		out_len = ((size_t)~0) - (size_t)out_buf; /* no limit */
+		if (!out_len)
+			out_len = ((size_t)~0) - (size_t)out_buf; /* no limit */
 	}
 	if (!out_buf) {
 		error("Out of memory while allocating output buffer");
@@ -181,4 +182,24 @@ gunzip_nomem1:
 	return rc; /* returns Z_OK (0) if successful */
 }
 
-#define decompress gunzip
+#ifndef PREBOOT
+STATIC int INIT gunzip(unsigned char *buf, long len,
+		       long (*fill)(void*, unsigned long),
+		       long (*flush)(void*, unsigned long),
+		       unsigned char *out_buf,
+		       long *pos,
+		       void (*error)(char *x))
+{
+	return __gunzip(buf, len, fill, flush, out_buf, 0, pos, error);
+}
+#else
+STATIC int INIT __decompress(unsigned char *buf, long len,
+			   long (*fill)(void*, unsigned long),
+			   long (*flush)(void*, unsigned long),
+			   unsigned char *out_buf, long out_len,
+			   long *pos,
+			   void (*error)(char *x))
+{
+	return __gunzip(buf, len, fill, flush, out_buf, out_len, pos, error);
+}
+#endif