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authorTony Battersby <tonyb@cybernetics.com>2009-02-11 13:24:19 -0800
committerDavid Woodhouse <David.Woodhouse@intel.com>2009-02-14 08:33:34 +0000
commit084eb960e81505680a9963665722d1bfd94af6a7 (patch)
treecfb6ed5b4449b4ae22b941529ece53ce0c705217 /drivers/pci/dmar.c
parent704126ad81b8cb7d3d70adb9ecb143f4d3fb38af (diff)
downloadop-kernel-dev-084eb960e81505680a9963665722d1bfd94af6a7.zip
op-kernel-dev-084eb960e81505680a9963665722d1bfd94af6a7.tar.gz
intel-iommu: fix endless "Unknown DMAR structure type" loop
I have a SuperMicro C2SBX motherboard with BIOS revision 1.0b. With vt-d enabled in the BIOS, Linux gets into an endless loop printing "DMAR:Unknown DMAR structure type" when booting. Here is the DMAR ACPI table: DMAR @ 0x7fe86dec 0000: 44 4d 41 52 98 00 00 00 01 6f 49 6e 74 65 6c 20 DMAR.....oIntel 0010: 4f 45 4d 44 4d 41 52 20 00 00 04 06 4c 4f 48 52 OEMDMAR ....LOHR 0020: 01 00 00 00 23 00 00 00 00 00 00 00 00 00 00 00 ....#........... 0030: 01 00 58 00 00 00 00 00 00 a0 e8 7f 00 00 00 00 ..X............. 0040: ff ff ef 7f 00 00 00 00 01 08 00 00 00 00 1d 00 ................ 0050: 01 08 00 00 00 00 1d 01 01 08 00 00 00 00 1d 02 ................ 0060: 01 08 00 00 00 00 1d 07 01 08 00 00 00 00 1a 00 ................ 0070: 01 08 00 00 00 00 1a 01 01 08 00 00 00 00 1a 02 ................ 0080: 01 08 00 00 00 00 1a 07 01 08 00 00 00 00 1a 07 ................ 0090: c0 00 68 00 04 10 66 60 ..h...f` Here are the messages printed by the kernel: DMAR:Host address width 36 DMAR:RMRR base: 0x000000007fe8a000 end: 0x000000007fefffff DMAR:Unknown DMAR structure type DMAR:Unknown DMAR structure type DMAR:Unknown DMAR structure type ... Although I not very familiar with ACPI, to me it looks like struct acpi_dmar_header::length == 0x0058 is incorrect, causing parse_dmar_table() to look at an invalid offset on the next loop. This offset happens to have struct acpi_dmar_header::length == 0x0000, which prevents the loop from ever terminating. This patch checks for this condition and bails out instead of looping forever. Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/pci/dmar.c')
-rw-r--r--drivers/pci/dmar.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 8d3e9c2..26c536b 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -330,6 +330,14 @@ parse_dmar_table(void)
entry_header = (struct acpi_dmar_header *)(dmar + 1);
while (((unsigned long)entry_header) <
(((unsigned long)dmar) + dmar_tbl->length)) {
+ /* Avoid looping forever on bad ACPI tables */
+ if (entry_header->length == 0) {
+ printk(KERN_WARNING PREFIX
+ "Invalid 0-length structure\n");
+ ret = -EINVAL;
+ break;
+ }
+
dmar_table_print_dmar_entry(entry_header);
switch (entry_header->type) {
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