From d54423c62c2f687919d4e5bdd4bb064234ff2d44 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Thu, 18 Feb 2010 01:50:31 +0100 Subject: [PATCH] firewire: core: fix "giving up on config rom" with Panasonic AG-DV2500 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 --- drivers/firewire/core-device.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c index eecd52dc8e9..e02bf2dff84 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 #include #include #include @@ -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; -- 2.20.1