binfmt_flat: allow compressed flat binary format to work on MMU systems

Let's take the simple and obvious approach by decompressing the binary
into a kernel buffer and then copying it to user space.  Those who are
looking for top performance on an MMU system are unlikely to choose this
executable format anyway.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

1 files changed, 42 insertions, 2 deletions

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 506139bfdc9e..9b2917a30294 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -34,6 +34,7 @@
 #include <linux/init.h>
 #include <linux/flat.h>
 #include <linux/uaccess.h>
+#include <linux/vmalloc.h>
 
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
@@ -628,6 +629,7 @@ static int load_flat_file(struct linux_binprm *bprm,
                  * load it all in and treat it like a RAM load from now on
                  */
                 if (flags & FLAT_FLAG_GZIP) {
+#ifndef CONFIG_MMU
                         result = decompress_exec(bprm, sizeof(struct flat_hdr),
                                          (((char *)textpos) + sizeof(struct flat_hdr)),
                                          (text_len + full_data
@@ -635,13 +637,51 @@ static int load_flat_file(struct linux_binprm *bprm,
                                          0);
                         memmove((void *) datapos, (void *) realdatastart,
                                         full_data);
+#else
+                        /*
+                         * This is used on MMU systems mainly for testing.
+                         * Let's use a kernel buffer to simplify things.
+                         */
+                        long unz_text_len = text_len - sizeof(struct flat_hdr);
+                        long unz_len = unz_text_len + full_data;
+                        char *unz_data = vmalloc(unz_len);
+                        if (!unz_data) {
+                                result = -ENOMEM;
+                        } else {
+                                result = decompress_exec(bprm, sizeof(struct flat_hdr),
+                                                         unz_data, unz_len, 0);
+                                if (result == 0 &&
+                                    (copy_to_user((void __user *)textpos + sizeof(struct flat_hdr),
+                                                  unz_data, unz_text_len) ||
+                                     copy_to_user((void __user *)datapos,
+                                                  unz_data + unz_text_len, full_data)))
+                                        result = -EFAULT;
+                                vfree(unz_data);
+                        }
+#endif
                 } else if (flags & FLAT_FLAG_GZDATA) {
                         result = read_code(bprm->file, textpos, 0, text_len);
-                        if (!IS_ERR_VALUE(result))
+                        if (!IS_ERR_VALUE(result)) {
+#ifndef CONFIG_MMU
                                 result = decompress_exec(bprm, text_len, (char *) datapos,
                                                  full_data, 0);
-                } else
+#else
+                                char *unz_data = vmalloc(full_data);
+                                if (!unz_data) {
+                                        result = -ENOMEM;
+                                } else {
+                                        result = decompress_exec(bprm, text_len,
+                                                       unz_data, full_data, 0);
+                                        if (result == 0 &&
+                                            copy_to_user((void __user *)datapos,
+                                                         unz_data, full_data))
+                                                result = -EFAULT;
+                                        vfree(unz_data);
+                                }
 #endif
+                        }
+                } else
+#endif /* CONFIG_BINFMT_ZFLAT */
                 {
                         result = read_code(bprm->file, textpos, 0, text_len);
                         if (!IS_ERR_VALUE(result))