linux-kernel - Re: [PATCH] iommu/vt-d: avoid invalid memory access via node_online(NUMA_NO

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Message-ID: <Ys2aoyVn7lc9VIUO@smile.fi.intel.com>
Date:   Tue, 12 Jul 2022 19:00:35 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Alexander Lobakin <alexandr.lobakin@...el.com>
Cc:     Yury Norov <yury.norov@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        kernel test robot <oliver.sang@...el.com>,
        iommu@...ts.linux.dev, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/vt-d: avoid invalid memory access via
 node_online(NUMA_NO_NODE)

On Tue, Jul 12, 2022 at 05:38:36PM +0200, Alexander Lobakin wrote:
> 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.

Yes, and bitops performance is critical, so it's caller's responsibility to
supply correct bit number.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> Fixes: ee34b32d8c29 ("dmar: support for parsing Remapping Hardware Static Affinity structure")
> Cc: stable@...r.kernel.org # 2.6.33+
> Reported-by: kernel test robot <oliver.sang@...el.com>
> Signed-off-by: Alexander Lobakin <alexandr.lobakin@...el.com>
> ---
>  drivers/iommu/intel/dmar.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 9699ca101c62..64b14ac4c7b0 100644
> --- 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;
> -- 
> 2.36.1
> 

-- 
With Best Regards,
Andy Shevchenko