kbuild: make modpost detect unterminated device id lists

Cause modpost to fail if any device id lists are incorrectly terminated,
after reporting the offender.
Improved reporting by akpm

Signed-off-by: Kees Cook <kees@ubuntu.com>
Cc: Greg KH <greg@kroah.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Ben Collins <bcollins@ubuntu.com>
Cc: Michael Wu <flamingice@sourmilk.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 33 insertions, 7 deletions

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 36e3754db53a..7abee0f2d207 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -55,10 +55,14 @@ do {                                                            \
  * Check that sizeof(device_id type) are consistent with size of section
  * in .o file. If in-consistent then userspace and kernel does not agree
  * on actual size which is a bug.
+ * Also verify that the final entry in the table is all zeros.
  **/
-static void device_id_size_check(const char *modname, const char *device_id,
-                                 unsigned long size, unsigned long id_size)
+static void device_id_check(const char *modname, const char *device_id,
+                            unsigned long size, unsigned long id_size,
+                            void *symval)
 {
+        int i;
+
         if (size % id_size || size < id_size) {
                 fatal("%s: sizeof(struct %s_device_id)=%lu is not a modulo "
                       "of the size of section __mod_%s_device_table=%lu.\n"
@@ -66,6 +70,20 @@ static void device_id_size_check(const char *modname, const char *device_id,
                       "in mod_devicetable.h\n",
                       modname, device_id, id_size, device_id, size, device_id);
         }
+        /* Verify last one is a terminator */
+        for (i = 0; i < id_size; i++ ) {
+                if (*(uint8_t*)(symval+size-id_size+i)) {
+                        fprintf(stderr,"%s: struct %s_device_id is %lu bytes.  "
+                                "The last of %lu is:\n",
+                                modname, device_id, id_size, size / id_size);
+                        for (i = 0; i < id_size; i++ )
+                                fprintf(stderr,"0x%02x ",
+                                        *(uint8_t*)(symval+size-id_size+i) );
+                        fprintf(stderr,"\n");
+                        fatal("%s: struct %s_device_id is not terminated "
+                                "with a NULL entry!\n", modname, device_id);
+                }
+        }
 }
 
 /* USB is special because the bcdDevice can be matched against a numeric range */
@@ -168,7 +186,7 @@ static void do_usb_table(void *symval, unsigned long size,
         unsigned int i;
         const unsigned long id_size = sizeof(struct usb_device_id);
 
-        device_id_size_check(mod->name, "usb", size, id_size);
+        device_id_check(mod->name, "usb", size, id_size, symval);
 
         /* Leave last one: it's the terminator. */
         size -= id_size;
@@ -535,7 +553,7 @@ static void do_table(void *symval, unsigned long size,
         char alias[500];
         int (*do_entry)(const char *, void *entry, char *alias) = function;
 
-        device_id_size_check(mod->name, device_id, size, id_size);
+        device_id_check(mod->name, device_id, size, id_size, symval);
         /* Leave last one: it's the terminator. */
         size -= id_size;
 
@@ -557,14 +575,21 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
                         Elf_Sym *sym, const char *symname)
 {
         void *symval;
+        char *zeros = NULL;
 
         /* We're looking for a section relative symbol */
         if (!sym->st_shndx || sym->st_shndx >= info->hdr->e_shnum)
                 return;
 
-        symval = (void *)info->hdr
-                + info->sechdrs[sym->st_shndx].sh_offset
-                + sym->st_value;
+        /* Handle all-NULL symbols allocated into .bss */
+        if (info->sechdrs[sym->st_shndx].sh_type & SHT_NOBITS) {
+                zeros = calloc(1, sym->st_size);
+                symval = zeros;
+        } else {
+                symval = (void *)info->hdr
+                        + info->sechdrs[sym->st_shndx].sh_offset
+                        + sym->st_value;
+        }
 
         if (sym_is(symname, "__mod_pci_device_table"))
                 do_table(symval, sym->st_size,
@@ -637,6 +662,7 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
                 do_table(symval, sym->st_size,
                          sizeof(struct ssb_device_id), "ssb",
                          do_ssb_entry, mod);
+        free(zeros);
 }
 
 /* Now add out buffered information to the generated C source */