5.15-stable review patch. If anyone has any objections, please let me know.
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From: Huacai Chen chenhuacai@loongson.cn
commit e416f0ed3c500c05c55fb62ee62662717b1c7f71 upstream.
BootLoaders (Grub, LILO, etc) may pass an identifier such as "BOOT_IMAGE= /boot/vmlinuz-x.y.z" to kernel parameters. But these identifiers are not recognized by the kernel itself so will be passed to userspace. However user space init program also don't recognize it.
KEXEC/KDUMP (kexec-tools) may also pass an identifier such as "kexec" on some architectures.
We cannot change BootLoader's behavior, because this behavior exists for many years, and there are already user space programs search BOOT_IMAGE= in /proc/cmdline to obtain the kernel image locations:
https://github.com/linuxdeepin/deepin-ab-recovery/blob/master/util.go (search getBootOptions) https://github.com/linuxdeepin/deepin-ab-recovery/blob/master/main.go (search getKernelReleaseWithBootOption) So the the best way is handle (ignore) it by the kernel itself, which can avoid such boot warnings (if we use something like init=/bin/bash, bootloader identifier can even cause a crash):
Kernel command line: BOOT_IMAGE=(hd0,1)/vmlinuz-6.x root=/dev/sda3 ro console=tty Unknown kernel command line parameters "BOOT_IMAGE=(hd0,1)/vmlinuz-6.x", will be passed to user space.
[chenhuacai@loongson.cn: use strstarts()] Link: https://lkml.kernel.org/r/20250815090120.1569947-1-chenhuacai@loongson.cn Link: https://lkml.kernel.org/r/20250721101343.3283480-1-chenhuacai@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Cc: Al Viro viro@zeniv.linux.org.uk Cc: Christian Brauner brauner@kernel.org Cc: Jan Kara jack@suse.cz Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- init/main.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/init/main.c +++ b/init/main.c @@ -540,6 +540,14 @@ static int __init unknown_bootoption(cha const char *unused, void *arg) { size_t len = strlen(param); + int i; + + /* + * Well-known bootloader identifiers: + * 1. LILO/Grub pass "BOOT_IMAGE=..."; + * 2. kexec/kdump (kexec-tools) pass "kexec". + */ + const char *bootloader[] = { "BOOT_IMAGE=", "kexec", NULL };
/* Handle params aliased to sysctls */ if (sysctl_is_alias(param)) @@ -547,6 +555,12 @@ static int __init unknown_bootoption(cha
repair_env_string(param, val);
+ /* Handle bootloader identifier */ + for (i = 0; bootloader[i]; i++) { + if (strstarts(param, bootloader[i])) + return 0; + } + /* Handle obsolete-style parameters */ if (obsolete_checksetup(param)) return 0;