[PATCH] x86: zimage: fix NULL pointer dereference in build_command_line

[Anton Moryakov]

Static analysis reported a redundant NULL check at line 68, but the
real issue is that env_command_line (from env_get("bootargs")) can
be NULL and is dereferenced unconditionally by strstr() at line 56.

If the "bootargs" environment variable is not set, env_get() returns
NULL, causing strstr(NULL, ...) to dereference a null pointer and crash.

Fix: add NULL check before strstr() call:
  if (env_command_line && !strstr(env_command_line, "console="))

The existing check at line 68 remains necessary to guard the strcat()
call and is no longer redundant.

Signed-off-by: Anton Moryakov <ant.v.moryakov at gmail.com>
---
 arch/x86/lib/zimage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
index a5f2231aa52..dbec5887b77 100644
--- a/arch/x86/lib/zimage.c
+++ b/arch/x86/lib/zimage.c
@@ -64,7 +64,7 @@ static void build_command_line(char *command_line, int auto_boot)
 	env_command_line =  env_get("bootargs");
 
 	/* set console= argument if we use a serial console */
-	if (!strstr(env_command_line, "console=")) {
+	if (env_command_line && !strstr(env_command_line, "console=")) {
 		if (!strcmp(env_get("stdout"), "serial")) {
 
 			/* We seem to use serial console */
-- 
2.39.2