Re: [PATCH v4] cxl: Fix possible null pointer dereference in read_handle()
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2024-07-19 01:25:51
Also in:
lkml, stable
Ma Ke [off-list ref] 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 <redacted>
---Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) In practice I don't this bug is triggerable, because the device tree that's being parsed comes from a single source (IBM hypervisor), and if this property was malformed that would simply be considered a bug in the hypervisor. cheers
quoted hunk ↗ jump to hunk
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) */-- 2.25.1