On Mon, Jul 15, 2024 at 04:28:15PM +1000, Michael Ellerman wrote:
Ma Ke make24@iscas.ac.cn 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@vger.kernel.org Fixes: 14baf4d9c739 ("cxl: Add guest-specific code") Signed-off-by: Ma Ke make24@iscas.ac.cn
The bug is real and the fix looks okay to me. I'm surprised that Smatch doesn't print a warning about "size" being uninitialized. I must not have it enabled in the .configs that I test. But I also wouldn't have reported that because it's from 2016 so it's too old.
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.
You're a domain expert so I trust you, but as a static checker person, there is no way I'd feel comfortable sending a patch like that... It's way too complicated and I wouldn't be able to test it. If this were my patch I would ask you to handle send that patch and give me Reported-by credit.
regards, dan carpenter