On 27/06/2025 13:23, Yao Zi wrote:
On Fri, Jun 27, 2025 at 12:51:02PM +0100, Andrew Goodbody wrote:
The local variable ranges may be used uninitialised if the function
fdt_get_dma_range is called with node < 0. Ensure this does not
happen by initialising ranges when declared.
It doesn't harm. When node < 0, parent is less than zero as well, and
the first while loop is skipped. The control flow just fails into the
error path where parent < 0 stays true.
OK, I will withdraw the patch. It just does not seem a great idea to
have an uninitialised variable evaluated even if the result of that
evaluation is irrelevant due to the second term in the logical OR being
true.
Furthermore, it doesn't seem valid to call fdt_get_dma_range() with a
negative node parameter, does it?
No it does not, but that is a different issue. Just because it is not
valid does not mean it will never happen.
Andrew
/**
* fdt_get_dma_range() - get DMA ranges to perform bus/cpu translations
*
* @blob: pointer to device tree blob
* @node_offset: node DT offset
* @cpu: pointer to variable storing the range's cpu address
* @bus: pointer to variable storing the range's bus address
* @size: pointer to variable storing the range's size
*
* Get DMA ranges for a specifc node, this is useful to perform bus->cpu and
* cpu->bus address translations
*
* Return: translated DMA address or OF_BAD_ADDR on error
*/
int fdt_get_dma_range(const void *blob, int node_offset, phys_addr_t *cpu,
dma_addr_t *bus, u64 *size);
Regards,
Yao Zi
This issue was found with Smatch.
Signed-off-by: Andrew Goodbody <[email protected]>
---
boot/fdt_support.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/boot/fdt_support.c b/boot/fdt_support.c
index 92f2f534ee0..4f63ce9a763 100644
--- a/boot/fdt_support.c
+++ b/boot/fdt_support.c
@@ -1547,7 +1547,7 @@ int fdt_get_dma_range(const void *blob, int node,
phys_addr_t *cpu,
{
bool found_dma_ranges = false;
struct of_bus *bus_node;
- const fdt32_t *ranges;
+ const fdt32_t *ranges = NULL;
int na, ns, pna, pns;
int parent = node;
int ret = 0;
---
base-commit: 359e3012921f2fc2d43f3c4e320a752173f82b82
change-id: 20250627-boot_fdt_fix-e4e56d956c8a
Best regards,
--
Andrew Goodbody <[email protected]>
