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.

Signed-off-by: Yinghai Lu <ying...@kernel.org>
Fixes: 1431574a1c4 (lib/decompressors: fix "no limit" output buffer length)
Cc: Alexandre Courbot <acour...@nvidia.com>
Cc: Jon Medhurst <t...@linaro.org>
Cc: Stephen Warren <swar...@wwwdotorg.org>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: stable <sta...@vger.kernel.org>

---
 arch/x86/boot/compressed/misc.c |    3 ++-
 lib/decompress_bunzip2.c        |    9 +++++++++
 lib/decompress_inflate.c        |   40 +++++++++++++++++++++++++++++++++++-----
 lib/decompress_unlz4.c          |   10 ++++++++++
 lib/decompress_unlzma.c         |   10 ++++++++++
 lib/decompress_unlzo.c          |   22 +++++++++++++++++++++-
 lib/decompress_unxz.c           |   21 ++++++++++++++++++++-
 7 files changed, 107 insertions(+), 8 deletions(-)

Index: linux-2.6/arch/x86/boot/compressed/misc.c
===================================================================
--- linux-2.6.orig/arch/x86/boot/compressed/misc.c
+++ linux-2.6/arch/x86/boot/compressed/misc.c
@@ -448,7 +448,8 @@ asmlinkage __visible void *decompress_ke
 #endif
 
        debug_putstr("\nDecompressing Linux... ");
-       decompress(input_data, input_len, NULL, NULL, output, NULL, error);
+       __decompress(input_data, input_len, NULL, NULL, output, output_len,
+                       NULL, error);
        parse_elf(output);
        /*
         * 32-bit always performs relocations. 64-bit relocations are only
Index: linux-2.6/lib/decompress_bunzip2.c
===================================================================
--- linux-2.6.orig/lib/decompress_bunzip2.c
+++ linux-2.6/lib/decompress_bunzip2.c
@@ -752,4 +752,13 @@ STATIC int INIT decompress(unsigned char
 {
        return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error);
 }
+STATIC int INIT __decompress(unsigned char *buf, long len,
+                       long (*fill)(void*, unsigned long),
+                       long (*flush)(void*, unsigned long),
+                       unsigned char *outbuf, long olen,
+                       long *pos,
+                       void (*error)(char *x))
+{
+       return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error);
+}
 #endif
Index: linux-2.6/lib/decompress_inflate.c
===================================================================
--- linux-2.6.orig/lib/decompress_inflate.c
+++ linux-2.6/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, un
 }
 
 /* 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 +182,33 @@ gunzip_nomem1:
        return rc; /* returns Z_OK (0) if successful */
 }
 
-#define decompress gunzip
+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);
+}
+
+#ifdef PREBOOT
+STATIC int INIT decompress(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, pos, error);
+}
+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
Index: linux-2.6/lib/decompress_unlz4.c
===================================================================
--- linux-2.6.orig/lib/decompress_unlz4.c
+++ linux-2.6/lib/decompress_unlz4.c
@@ -206,4 +206,14 @@ STATIC int INIT decompress(unsigned char
 {
        return unlz4(buf, in_len - 4, fill, flush, output, posp, error);
 }
+STATIC int INIT __decompress(unsigned char *buf, long in_len,
+                             long (*fill)(void*, unsigned long),
+                             long (*flush)(void*, unsigned long),
+                             unsigned char *output, long out_len,
+                             long *posp,
+                             void (*error)(char *x)
+       )
+{
+       return unlz4(buf, in_len - 4, fill, flush, output, posp, error);
+}
 #endif
Index: linux-2.6/lib/decompress_unlzma.c
===================================================================
--- linux-2.6.orig/lib/decompress_unlzma.c
+++ linux-2.6/lib/decompress_unlzma.c
@@ -677,4 +677,14 @@ STATIC int INIT decompress(unsigned char
 {
        return unlzma(buf, in_len - 4, fill, flush, output, posp, error);
 }
+STATIC int INIT __decompress(unsigned char *buf, long in_len,
+                             long (*fill)(void*, unsigned long),
+                             long (*flush)(void*, unsigned long),
+                             unsigned char *output, long out_len,
+                             long *posp,
+                             void (*error)(char *x)
+       )
+{
+       return unlzma(buf, in_len - 4, fill, flush, output, posp, error);
+}
 #endif
Index: linux-2.6/lib/decompress_unlzo.c
===================================================================
--- linux-2.6.orig/lib/decompress_unlzo.c
+++ linux-2.6/lib/decompress_unlzo.c
@@ -31,6 +31,7 @@
  */
 
 #ifdef STATIC
+#define PREBOOT
 #include "lzo/lzo1x_decompress_safe.c"
 #else
 #include <linux/decompress/unlzo.h>
@@ -287,4 +288,23 @@ exit:
        return ret;
 }
 
-#define decompress unlzo
+#ifdef PREBOOT
+STATIC int INIT decompress(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 unlzo(buf, len, fill, flush, out_buf, pos, error);
+}
+STATIC int INIT __decompress(unsigned char *buf, long len,
+                          long (*fill)(void*, unsigned long),
+                          long (*flush)(void*, unsigned long),
+                          unsigned char *out_buf, long olen,
+                          long *pos,
+                          void (*error)(char *x))
+{
+       return unlzo(buf, len, fill, flush, out_buf, pos, error);
+}
+#endif
Index: linux-2.6/lib/decompress_unxz.c
===================================================================
--- linux-2.6.orig/lib/decompress_unxz.c
+++ linux-2.6/lib/decompress_unxz.c
@@ -394,4 +394,23 @@ error_alloc_state:
  * This macro is used by architecture-specific files to decompress
  * the kernel image.
  */
-#define decompress unxz
+#ifdef XZ_PREBOOT
+STATIC int INIT decompress(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 unxz(buf, len, fill, flush, out_buf, pos, error);
+}
+STATIC int INIT __decompress(unsigned char *buf, long len,
+                          long (*fill)(void*, unsigned long),
+                          long (*flush)(void*, unsigned long),
+                          unsigned char *out_buf, long olen,
+                          long *pos,
+                          void (*error)(char *x))
+{
+       return unxz(buf, len, fill, flush, out_buf, pos, error);
+}
+#endif
--
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