1 files changed, 22 insertions, 10 deletions

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index eecd52dc8e98..e02bf2dff845 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -18,6 +18,7 @@
  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
+#include <linux/bug.h>
 #include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -580,11 +581,7 @@ static int read_bus_info_block(struct fw_device *device, int generation)
                  */
                 key = stack[--sp];
                 i = key & 0xffffff;
-                if (i >= READ_BIB_ROM_SIZE)
-                        /*
-                         * The reference points outside the standard
-                         * config rom area, something's fishy.
-                         */
+                if (WARN_ON(i >= READ_BIB_ROM_SIZE))
                         goto out;
 
                 /* Read header quadlet for the block to get the length. */
@@ -606,14 +603,29 @@ static int read_bus_info_block(struct fw_device *device, int generation)
                  * block, check the entries as we read them to see if
                  * it references another block, and push it in that case.
                  */
-                while (i < end) {
+                for (; i < end; i++) {
                         if (read_rom(device, generation, i, &rom[i]) !=
                             RCODE_COMPLETE)
                                 goto out;
-                        if ((key >> 30) == 3 && (rom[i] >> 30) > 1 &&
-                            sp < READ_BIB_STACK_SIZE)
-                                stack[sp++] = i + rom[i];
-                        i++;
+
+                        if ((key >> 30) != 3 || (rom[i] >> 30) < 2 ||
+                            sp >= READ_BIB_STACK_SIZE)
+                                continue;
+                        /*
+                         * Offset points outside the ROM.  May be a firmware
+                         * bug or an Extended ROM entry (IEEE 1212-2001 clause
+                         * 7.7.18).  Simply overwrite this pointer here by a
+                         * fake immediate entry so that later iterators over
+                         * the ROM don't have to check offsets all the time.
+                         */
+                        if (i + (rom[i] & 0xffffff) >= READ_BIB_ROM_SIZE) {
+                                fw_error("skipped unsupported ROM entry %x at %llx\n",
+                                         rom[i],
+                                         i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
+                                rom[i] = 0;
+                                continue;
+                        }
+                        stack[sp++] = i + rom[i];
                 }
                 if (length < i)
                         length = i;