[PATCH 1/3] firewire: core: fix "giving up on config rom" with Panasonic AG-DV2500

[PATCH 1/3] firewire: core: fix "giving up on config rom" with Panasonic AG-DV2500

[Stefan Richter]

The Panasonic AG-DV2500 tape deck contains an invalid entry in its
configuration ROM root directory:  A leaf pointer with the undefined key
ID 0 and an offset that points way out of the standard config ROM area.
This caused firewire-core to dismiss the device with the generic log
message "giving up on config rom for node id...", after which it was of
course impossible to access the tape deck with dvgrab or any other
program.  https://bugzilla.redhat.com/show_bug.cgi?id=449252#c29

The fix is to simply ignore this invalid ROM entry and proceed to read
the valid rest of the ROM.  There is a catch though:  When the kernel
later iterates over the ROM, it would be nasty having to check again for
such too large ROM offsets.  Therefore we manipulate the defective or
unsupported ROM entry to become a harmless immediate entry that won't
have any side effects later (an entry with the value 0x00000000).

Reported-by: George Chriss
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-device.c |   32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

Index: linux-2.6.33-rc8/drivers/firewire/core-device.c
===================================================================
--- linux-2.6.33-rc8.orig/drivers/firewire/core-device.c
+++ linux-2.6.33-rc8/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
 		 */
 		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
 		 * 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;

-- 
Stefan Richter
-=====-==-=- --=- =--=-
http://arcgraph.de/sr/

[PATCH 2/3] firewire: core: don't fail device creation in case of too large config ROM blocks

[Stefan Richter]

It never happened yet, but better safe than sorry:  If a device's config
ROM contains a block which overlaps the boundary at 0xfffff00007ff, just
ignore that one block instead of refusing to add the device
representation.  That way, upper layers (kernelspace or userspace
drivers) might still be able to use the device to some degree.

That's better than total inaccessibility of the device.  Worse, the core
would have logged only a generic "giving up on config rom" message which
could only be debugged by feeding a firewire-ohci debug logging session
through a config ROM interpreter, IOW would likely remain undiagnosed.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-device.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

Index: linux-2.6.33-rc8/drivers/firewire/core-device.c
===================================================================
--- linux-2.6.33-rc8.orig/drivers/firewire/core-device.c
+++ linux-2.6.33-rc8/drivers/firewire/core-device.c
@@ -588,15 +588,19 @@ static int read_bus_info_block(struct fw
 		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
 			goto out;
 		end = i + (rom[i] >> 16) + 1;
-		i++;
-		if (end > READ_BIB_ROM_SIZE)
+		if (end > READ_BIB_ROM_SIZE) {
 			/*
-			 * This block extends outside standard config
-			 * area (and the array we're reading it
-			 * into).  That's broken, so ignore this
-			 * device.
+			 * This block extends outside the config ROM which is
+			 * a firmware bug.  Ignore this whole block, i.e.
+			 * simply set a fake block length of 0.
 			 */
-			goto out;
+			fw_error("skipped invalid ROM block %x at %llx\n",
+				 rom[i],
+				 i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
+			rom[i] = 0;
+			end = i;
+		}
+		i++;
 
 		/*
 		 * Now read in the block.  If this is a directory

-- 
Stefan Richter
-=====-==-=- --=- =--=-
http://arcgraph.de/sr/

[PATCH 3/3] firewire: core: increase stack size of config ROM reader

[Stefan Richter]

The stack size of 16 was artificially chosen and may be too small in
extreme cases.  A device won't be accessible then.

Since it doesn't really matter to the slab allocator whether we ask for
1088 bytes or 2048 bytes of scratch memory, just allocate 2048 bytes for
the sum of temporary config ROM image and stack, and we will never ever
overflow the stack (because there simply can't be more stack items than
ROM entries).

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-device.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Index: linux-2.6.33-rc8/drivers/firewire/core-device.c
===================================================================
--- linux-2.6.33-rc8.orig/drivers/firewire/core-device.c
+++ linux-2.6.33-rc8/drivers/firewire/core-device.c
@@ -493,7 +493,6 @@ static int read_rom(struct fw_device *de
 }
 
 #define READ_BIB_ROM_SIZE	256
-#define READ_BIB_STACK_SIZE	16
 
 /*
  * Read the bus info block, perform a speed probe, and read all of the rest of
@@ -510,7 +509,7 @@ static int read_bus_info_block(struct fw
 	int i, end, length, ret = -1;
 
 	rom = kmalloc(sizeof(*rom) * READ_BIB_ROM_SIZE +
-		      sizeof(*stack) * READ_BIB_STACK_SIZE, GFP_KERNEL);
+		      sizeof(*stack) * READ_BIB_ROM_SIZE, GFP_KERNEL);
 	if (rom == NULL)
 		return -ENOMEM;
 
@@ -612,8 +611,7 @@ static int read_bus_info_block(struct fw
 			    RCODE_COMPLETE)
 				goto out;
 
-			if ((key >> 30) != 3 || (rom[i] >> 30) < 2 ||
-			    sp >= READ_BIB_STACK_SIZE)
+			if ((key >> 30) != 3 || (rom[i] >> 30) < 2)
 				continue;
 			/*
 			 * Offset points outside the ROM.  May be a firmware

-- 
Stefan Richter
-=====-==-=- --=- =--=-
http://arcgraph.de/sr/

[PATCH] firewire: core: fix an information leak

[Stefan Richter]

If a device exposes a sparsely populated configuration ROM,
firewire-core's sysfs interface and character device file interface
showed random data in the gaps between config ROM blocks.  Fix this by
zero-initialization of the config ROM reader's scratch buffer.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-device.c |    1 +
 1 file changed, 1 insertion(+)

Index: b/drivers/firewire/core-device.c
===================================================================
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -514,6 +514,7 @@ static int read_bus_info_block(struct fw
 		return -ENOMEM;
 
 	stack = &rom[READ_BIB_ROM_SIZE];
+	memset(rom, 0, sizeof(*rom) * READ_BIB_ROM_SIZE);
 
 	device->max_speed = SCODE_100;
 

-- 
Stefan Richter
-=====-==-=- --=- =--==
http://arcgraph.de/sr/

[PATCH] firewire: core: rename an internal function

[Stefan Richter]

according to what it really does.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
 drivers/firewire/core-device.c |   28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

Index: b/drivers/firewire/core-device.c
===================================================================
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -492,29 +492,29 @@ static int read_rom(struct fw_device *de
 	return rcode;
 }
 
-#define READ_BIB_ROM_SIZE	256
+#define MAX_CONFIG_ROM_SIZE 256
 
 /*
  * Read the bus info block, perform a speed probe, and read all of the rest of
  * the config ROM.  We do all this with a cached bus generation.  If the bus
- * generation changes under us, read_bus_info_block will fail and get retried.
+ * generation changes under us, read_config_rom will fail and get retried.
  * It's better to start all over in this case because the node from which we
  * are reading the ROM may have changed the ROM during the reset.
  */
-static int read_bus_info_block(struct fw_device *device, int generation)
+static int read_config_rom(struct fw_device *device, int generation)
 {
 	const u32 *old_rom, *new_rom;
 	u32 *rom, *stack;
 	u32 sp, key;
 	int i, end, length, ret = -1;
 
-	rom = kmalloc(sizeof(*rom) * READ_BIB_ROM_SIZE +
-		      sizeof(*stack) * READ_BIB_ROM_SIZE, GFP_KERNEL);
+	rom = kmalloc(sizeof(*rom) * MAX_CONFIG_ROM_SIZE +
+		      sizeof(*stack) * MAX_CONFIG_ROM_SIZE, GFP_KERNEL);
 	if (rom == NULL)
 		return -ENOMEM;
 
-	stack = &rom[READ_BIB_ROM_SIZE];
-	memset(rom, 0, sizeof(*rom) * READ_BIB_ROM_SIZE);
+	stack = &rom[MAX_CONFIG_ROM_SIZE];
+	memset(rom, 0, sizeof(*rom) * MAX_CONFIG_ROM_SIZE);
 
 	device->max_speed = SCODE_100;
 
@@ -581,14 +581,14 @@ static int read_bus_info_block(struct fw
 		 */
 		key = stack[--sp];
 		i = key & 0xffffff;
-		if (WARN_ON(i >= READ_BIB_ROM_SIZE))
+		if (WARN_ON(i >= MAX_CONFIG_ROM_SIZE))
 			goto out;
 
 		/* Read header quadlet for the block to get the length. */
 		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
 			goto out;
 		end = i + (rom[i] >> 16) + 1;
-		if (end > READ_BIB_ROM_SIZE) {
+		if (end > MAX_CONFIG_ROM_SIZE) {
 			/*
 			 * This block extends outside the config ROM which is
 			 * a firmware bug.  Ignore this whole block, i.e.
@@ -621,7 +621,7 @@ static int read_bus_info_block(struct fw
 			 * 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) {
+			if (i + (rom[i] & 0xffffff) >= MAX_CONFIG_ROM_SIZE) {
 				fw_error("skipped unsupported ROM entry %x at %llx\n",
 					 rom[i],
 					 i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
@@ -971,7 +971,7 @@ static void fw_device_init(struct work_s
 	 * device.
 	 */
 
-	if (read_bus_info_block(device, device->generation) < 0) {
+	if (read_config_rom(device, device->generation) < 0) {
 		if (device->config_rom_retries < MAX_RETRIES &&
 		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
 			device->config_rom_retries++;
@@ -1088,7 +1088,7 @@ enum {
 };
 
 /* Reread and compare bus info block and header of root directory */
-static int reread_bus_info_block(struct fw_device *device, int generation)
+static int reread_config_rom(struct fw_device *device, int generation)
 {
 	u32 q;
 	int i;
@@ -1114,7 +1114,7 @@ static void fw_device_refresh(struct wor
 	struct fw_card *card = device->card;
 	int node_id = device->node_id;
 
-	switch (reread_bus_info_block(device, device->generation)) {
+	switch (reread_config_rom(device, device->generation)) {
 	case REREAD_BIB_ERROR:
 		if (device->config_rom_retries < MAX_RETRIES / 2 &&
 		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
@@ -1148,7 +1148,7 @@ static void fw_device_refresh(struct wor
 	 */
 	device_for_each_child(&device->device, NULL, shutdown_unit);
 
-	if (read_bus_info_block(device, device->generation) < 0) {
+	if (read_config_rom(device, device->generation) < 0) {
 		if (device->config_rom_retries < MAX_RETRIES &&
 		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
 			device->config_rom_retries++;

-- 
Stefan Richter
-=====-==-=- --=- =--==
http://arcgraph.de/sr/