[PATCH] of: fdt: fix off-by-one error in unflatten_dt_nodes()

[PATCH] of: fdt: fix off-by-one error in unflatten_dt_nodes()

[Sergey Shtylyov]

Commit 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
forgot to fix up the depth check in the loop body in unflatten_dt_nodes()
which makes it possible to overflow the nps[] buffer...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Fixes: 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
The patch is against the 'master' branch of Rob Herring's 'linux-git' repo...

 drivers/of/fdt.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/drivers/of/fdt.c
===================================================================
--- linux.orig/drivers/of/fdt.c
+++ linux/drivers/of/fdt.c
@@ -314,7 +314,7 @@ static int unflatten_dt_nodes(const void
 	for (offset = 0;
 	     offset >= 0 && depth >= initial_depth;
 	     offset = fdt_next_node(blob, offset, &depth)) {
-		if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH))
+		if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH - 1))
 			continue;
 
 		if (!IS_ENABLED(CONFIG_OF_KOBJ) &&

Re: [PATCH] of: fdt: fix off-by-one error in unflatten_dt_nodes()

[Rob Herring]

On Sat, 13 Aug 2022 23:34:16 +0300, Sergey Shtylyov wrote:
> Commit 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
> forgot to fix up the depth check in the loop body in unflatten_dt_nodes()
> which makes it possible to overflow the nps[] buffer...
> 
> Found by Linux Verification Center (linuxtesting.org) with the SVACE static
> analysis tool.
> 
> Fixes: 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> 
> ---
> The patch is against the 'master' branch of Rob Herring's 'linux-git' repo...
> 
>  drivers/of/fdt.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Applied, thanks!