FAILED: patch "[PATCH] init: fix early boot crash with bare hostname parameter" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] init: fix early boot crash with bare hostname parameter" failed to apply to 6.6-stable tree

[Sasha Levin]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x b6bec5b63a5b812145e53aaad1e63661c7214f93
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107053215-failed-6.6-b6bec5b63a5b@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From b6bec5b63a5b812145e53aaad1e63661c7214f93 Mon Sep 17 00:00:00 2001
From: Thorsten Blum <blum@kernel.org>
Date: Wed, 26 Aug 2026 12:09:03 +0200
Subject: [PATCH] init: fix early boot crash with bare hostname parameter

When a bare hostname parameter is specified on the kernel command line
without the '=' separator, early parameter parsing passes NULL to
early_hostname(), which dereferences it in strscpy() and can crash the
system during early boot.

Reject NULL values in early_hostname() and return -EINVAL instead.

Link: https://lore.kernel.org/20260826100904.296151-2-blum@kernel.org
Fixes: 5a704629f2c1 ("init: add "hostname" kernel parameter")
Signed-off-by: Thorsten Blum <blum@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Moulding <dmoulding@me.com>
Cc: <stable@vger.kernel.org>
---
 init/version.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/init/version.c b/init/version.c
index 94c96f6fbfe6a..0bd5c45aabc46 100644
--- a/init/version.c
+++ b/init/version.c
@@ -23,6 +23,9 @@ static int __init early_hostname(char *arg)
 	size_t maxlen  = bufsize - 1;
 	ssize_t arglen;
 
+	if (!arg)
+		return -EINVAL;
+
 	arglen = strscpy(init_uts_ns.name.nodename, arg, bufsize);
 	if (arglen < 0) {
 		pr_warn("hostname parameter exceeds %zd characters and will be truncated",
-- 
2.53.0

[PATCH 6.6.y 1/2] init/version.c: Replace strlcpy with strscpy

[Sasha Levin]

From: Azeem Shaikh <azeemshaikh38@gmail.com>

[ Upstream commit 8ebab155ea18a6d6c47b17287a0ab4633334f6eb ]

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230830160806.3821893-1-azeemshaikh38@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Stable-dep-of: b6bec5b63a5b ("init: fix early boot crash with bare hostname parameter")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 init/version.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/init/version.c b/init/version.c
index f117921811b45..94c96f6fbfe6a 100644
--- a/init/version.c
+++ b/init/version.c
@@ -21,10 +21,10 @@ static int __init early_hostname(char *arg)
 {
 	size_t bufsize = sizeof(init_uts_ns.name.nodename);
 	size_t maxlen  = bufsize - 1;
-	size_t arglen;
+	ssize_t arglen;
 
-	arglen = strlcpy(init_uts_ns.name.nodename, arg, bufsize);
-	if (arglen > maxlen) {
+	arglen = strscpy(init_uts_ns.name.nodename, arg, bufsize);
+	if (arglen < 0) {
 		pr_warn("hostname parameter exceeds %zd characters and will be truncated",
 			maxlen);
 	}
-- 
2.53.0

[PATCH 6.6.y 2/2] init: fix early boot crash with bare hostname parameter

[Sasha Levin]

From: Thorsten Blum <blum@kernel.org>

[ Upstream commit b6bec5b63a5b812145e53aaad1e63661c7214f93 ]

When a bare hostname parameter is specified on the kernel command line
without the '=' separator, early parameter parsing passes NULL to
early_hostname(), which dereferences it in strscpy() and can crash the
system during early boot.

Reject NULL values in early_hostname() and return -EINVAL instead.

Link: https://lore.kernel.org/20260826100904.296151-2-blum@kernel.org
Fixes: 5a704629f2c1 ("init: add "hostname" kernel parameter")
Signed-off-by: Thorsten Blum <blum@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Moulding <dmoulding@me.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 init/version.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/init/version.c b/init/version.c
index 94c96f6fbfe6a..0bd5c45aabc46 100644
--- a/init/version.c
+++ b/init/version.c
@@ -23,6 +23,9 @@ static int __init early_hostname(char *arg)
 	size_t maxlen  = bufsize - 1;
 	ssize_t arglen;
 
+	if (!arg)
+		return -EINVAL;
+
 	arglen = strscpy(init_uts_ns.name.nodename, arg, bufsize);
 	if (arglen < 0) {
 		pr_warn("hostname parameter exceeds %zd characters and will be truncated",
-- 
2.53.0