[PATCH] arm64: pi: validate bootargs before parsing them

[Pengpeng Hou]

get_bootargs_cmdline() fetches the raw bootargs property from the FDT
and immediately calls strlen() on it before later passing the same
pointer into the early command-line parser. Flat DT properties are
external boot input, and this path does not prove that bootargs is
NUL-terminated within its declared bounds.

Use fdt_stringlist_get() so malformed unterminated bootargs are
rejected before the local parser treats them as C strings.

Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
---
 arch/arm64/kernel/pi/idreg-override.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index bc57b290e5e7..310ed279ef26 100644
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -373,11 +373,11 @@ static __init const u8 *get_bootargs_cmdline(const void *fdt, int node)
 	if (node < 0)
 		return NULL;
 
-	prop = fdt_getprop(fdt, node, bootargs, NULL);
+	prop = fdt_stringlist_get(fdt, node, bootargs, 0, NULL);
 	if (!prop)
 		return NULL;
 
-	return strlen(prop) ? prop : NULL;
+	return *prop ? prop : NULL;
 }
 
 static __init void parse_cmdline(const void *fdt, int chosen)
-- 
2.50.1 (Apple Git-155)