Hello Jordy,

On Tue, 1 Feb 2022 at 02:09, John Stultz john.stultz@linaro.org wrote:

On Sat, Jan 29, 2022 at 7:06 AM Jordy Zomer jordy@pwning.systems wrote:

...

It appears like nr could be a Spectre v1 gadget as it's supplied by a user and used as an array index. Prevent the contents of kernel memory from being leaked to userspace via speculative execution by using array_index_nospec.

Signed-off-by: Jordy Zomer jordy@pwning.systems

Thanks very much for your patch; I've pushed it to drm-misc-fixes, so we should see it in mainline soon.

...

---

drivers/dma-buf/dma-heap.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 56bf5ad01ad5..8f5848aa144f 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -14,6 +14,7 @@ #include <linux/xarray.h> #include <linux/list.h> #include <linux/slab.h> +#include <linux/nospec.h> #include <linux/uaccess.h> #include <linux/syscalls.h> #include <linux/dma-heap.h> @@ -135,6 +136,7 @@ static long dma_heap_ioctl(struct file *file, unsigned int ucmd, if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds)) return -EINVAL;

•   nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
    /* Get the kernel ioctl cmd that matches */
    kcmd = dma_heap_ioctl_cmds[nr];
  

Thanks for submitting this! It looks sane to me.

Acked-by: John Stultz john.stultz@linaro.org

thanks -john

Best, Sumit.