Re: [PATCH v2 3/4] dma-mapping: benchmark: fix node id validation

[Robin Murphy]

On 2024-05-04 12:47 pm, Fedor Pchelkin wrote:
> While validating node ids in map_benchmark_ioctl(), node_possible() may
> be provided with invalid argument outside of [0,MAX_NUMNODES-1] range
> leading to:
>
> BUG: KASAN: wild-memory-access in map_benchmark_ioctl (kernel/dma/map_benchmark.c:214)
> Read of size 8 at addr 1fffffff8ccb6398 by task dma_map_benchma/971
> CPU: 7 PID: 971 Comm: dma_map_benchma Not tainted 6.9.0-rc6 #37
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
> Call Trace:
>   <TASK>
> dump_stack_lvl (lib/dump_stack.c:117)
> kasan_report (mm/kasan/report.c:603)
> kasan_check_range (mm/kasan/generic.c:189)
> variable_test_bit (arch/x86/include/asm/bitops.h:227) [inline]
> arch_test_bit (arch/x86/include/asm/bitops.h:239) [inline]
> _test_bit at (include/asm-generic/bitops/instrumented-non-atomic.h:142) [inline]
> node_state (include/linux/nodemask.h:423) [inline]
> map_benchmark_ioctl (kernel/dma/map_benchmark.c:214)
> full_proxy_unlocked_ioctl (fs/debugfs/file.c:333)
> __x64_sys_ioctl (fs/ioctl.c:890)
> do_syscall_64 (arch/x86/entry/common.c:83)
> entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
>
> Compare node ids with sane bounds first. NUMA_NO_NODE is considered a
> special valid case meaning that benchmarking kthreads won't be bound to a
> cpuset of a given node.

Makes sense, and the style of the check looks like a reasonably common 
pattern.

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

> Found by Linux Verification Center (linuxtesting.org).
>
> Fixes: 65789daa8087 ("dma-mapping: add benchmark support for streaming DMA APIs")
> Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
> ---
>   kernel/dma/map_benchmark.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
> index a6edb1ef98c8..9f6c15f3f168 100644
> --- a/kernel/dma/map_benchmark.c
> +++ b/kernel/dma/map_benchmark.c
> @@ -212,7 +212,8 @@ static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
>   		}
>   
>   		if (map->bparam.node != NUMA_NO_NODE &&
> -		    !node_possible(map->bparam.node)) {
> +		    (map->bparam.node < 0 || map->bparam.node >= MAX_NUMNODES ||
> +		     !node_possible(map->bparam.node))) {
>   			pr_err("invalid numa node\n");
>   			return -EINVAL;
>   		}