git: 41cf74fe8ce5 - main - loader - guard against empty rootdev

The branch main has been updated by sjg:

URL: https://cgit.FreeBSD.org/src/commit/?id=41cf74fe8ce5c6f8f10aa074e9405043a242a2b1

commit 41cf74fe8ce5c6f8f10aa074e9405043a242a2b1
Author:     Simon J. Gerraty <sjg@FreeBSD.org>
AuthorDate: 2025-05-20 16:10:50 +0000
Commit:     Simon J. Gerraty <sjg@FreeBSD.org>
CommitDate: 2025-05-20 16:10:50 +0000

    loader - guard against empty rootdev
    
    At least one instance of u-boot pretending to be EFI
    is passing empty rootdev to loader which does not end well.
    
    A simple precaution is harmless.
    
    Reviewed by:    imp
    Differential Revision:  https://reviews.freebsd.org/D50334
---
 stand/common/metadata.c | 2 +-
 stand/efi/loader/main.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/stand/common/metadata.c b/stand/common/metadata.c
index 22df6f175791..715354aedd04 100644
--- a/stand/common/metadata.c
+++ b/stand/common/metadata.c
@@ -111,7 +111,7 @@ md_load_dual(char *args, vm_offset_t *modulep, vm_offset_t *dtb, int kern64)
      * tested/set by MI code before launching the kernel.
      */
     rootdevname = getenv("rootdev");
-    if (rootdevname == NULL)
+    if (rootdevname == NULL || *rootdevname == '\0')
 	rootdevname = getenv("currdev");
     /* Try reading the /etc/fstab file to select the root device */
     getrootmount(rootdevname);
diff --git a/stand/efi/loader/main.c b/stand/efi/loader/main.c
index 2384fd08b964..c9a842afb06d 100644
--- a/stand/efi/loader/main.c
+++ b/stand/efi/loader/main.c
@@ -513,7 +513,7 @@ find_currdev(bool do_bootmgr, bool is_last,
 	 * it's wrong.
 	 */
 	rootdev = getenv("rootdev");
-	if (rootdev != NULL) {
+	if (rootdev != NULL && *rootdev != '\0') {
 		printf("    Setting currdev to configured rootdev %s\n",
 		    rootdev);
 		set_currdev(rootdev);