Ma Ke <make24@xxxxxxxxxxx> writes:
> In read_handle(), of_get_address() may return NULL if getting address and
> size of the node failed. When of_read_number() uses prop to handle
> conversions between different byte orders, it could lead to a null pointer
> dereference. Add NULL check to fix potential issue.
>
> Found by static analysis.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 14baf4d9c739 ("cxl: Add guest-specific code")
> Signed-off-by: Ma Ke <make24@xxxxxxxxxxx>
> ---
> Changes in v4:
> - modified vulnerability description according to suggestions, making the
> process of static analysis of vulnerabilities clearer. No active research
> on developer behavior.
> Changes in v3:
> - fixed up the changelog text as suggestions.
> Changes in v2:
> - added an explanation of how the potential vulnerability was discovered,
> but not meet the description specification requirements.
> ---
> drivers/misc/cxl/of.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/misc/cxl/of.c b/drivers/misc/cxl/of.c
> index bcc005dff1c0..d8dbb3723951 100644
> --- a/drivers/misc/cxl/of.c
> +++ b/drivers/misc/cxl/of.c
> @@ -58,7 +58,7 @@ static int read_handle(struct device_node *np, u64 *handle)
>
> /* Get address and size of the node */
> prop = of_get_address(np, 0, &size, NULL);
> - if (size)
> + if (!prop || size)
> return -EINVAL;
>
> /* Helper to read a big number; size is in cells (not bytes) */
If you expand the context this could just use of_property_read_reg(),
something like below.
cheers
diff --git a/drivers/misc/cxl/of.c b/drivers/misc/cxl/of.c
index bcc005dff1c0..a184855b2a7b 100644
--- a/drivers/misc/cxl/of.c
+++ b/drivers/misc/cxl/of.c
@@ -53,16 +53,15 @@ static const __be64 *read_prop64_dword(const struct device_node *np,
static int read_handle(struct device_node *np, u64 *handle)
{
- const __be32 *prop;
u64 size;
+
+ if (of_property_read_reg(np, 0, handle, &size))
+ return -EINVAL;
- /* Get address and size of the node */
- prop = of_get_address(np, 0, &size, NULL);
+ // Size must be zero per PAPR+ v2.13 § C.6.19
if (size)
return -EINVAL;
- /* Helper to read a big number; size is in cells (not bytes) */
- *handle = of_read_number(prop, of_n_addr_cells(np));
return 0;
}
