iommu/vt-d: avoid invalid memory access via node_online(NUMA_NO_NODE)

KASAN reports:

[ 4.668325][ T0] BUG: KASAN: wild-memory-access in dmar_parse_one_rhsa (arch/x86/include/asm/bitops.h:214 arch/x86/include/asm/bitops.h:226 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/nodemask.h:415 drivers/iommu/intel/dmar.c:497)
[    4.676149][    T0] Read of size 8 at addr 1fffffff85115558 by task swapper/0/0
[    4.683454][    T0]
[    4.685638][    T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc3-00004-g0e862838f290 #1
[    4.694331][    T0] Hardware name: Supermicro SYS-5018D-FN4T/X10SDV-8C-TLN4F, BIOS 1.1 03/02/2016
[    4.703196][    T0] Call Trace:
[    4.706334][    T0]  <TASK>
[ 4.709133][ T0] ? dmar_parse_one_rhsa (arch/x86/include/asm/bitops.h:214 arch/x86/include/asm/bitops.h:226 include/asm-generic/bitops/instrumented-non-atomic.h:142 include/linux/nodemask.h:415 drivers/iommu/intel/dmar.c:497)

after converting the type of the first argument (@nr, bit number)
of arch_test_bit() from `long` to `unsigned long`[0].

Under certain conditions (for example, when ACPI NUMA is disabled
via command line), pxm_to_node() can return %NUMA_NO_NODE (-1).
It is valid 'magic' number of NUMA node, but not valid bit number
to use in bitops.
node_online() eventually descends to test_bit() without checking
for the input, assuming it's on caller side (which might be good
for perf-critical tasks). There, -1 becomes %ULONG_MAX which leads
to an insane array index when calculating bit position in memory.

For now, add an explicit check for @node being not %NUMA_NO_NODE
before calling test_bit(). The actual logics didn't change here
at all.

[0] https://github.com/norov/linux/commit/d59311fead6d25ca4499fb6b2333f71d93bbc19d

Fixes: 576524892222 ("dmar: support for parsing Remapping Hardware Static Affinity structure")
Cc: stable@vger.kernel.org # 2.6.33+
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 592c1e1a5d4b975354db850f4dde86873af3b20d..70d324c9894a1bb340ffd066a9dd1314bd97e2f0 100644 (file)
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -494,7 +494,7 @@ static int dmar_parse_one_rhsa(struct acpi_dmar_header *header, void *arg)
                if (drhd->reg_base_addr == rhsa->base_address) {
                        int node = pxm_to_node(rhsa->proximity_domain);
 
-                       if (!node_online(node))
+                       if (node != NUMA_NO_NODE && !node_online(node))
                                node = NUMA_NO_NODE;
                        drhd->iommu->node = node;
                        return 0;