bootconfig: Fix to remove bootconfig data from initrd while boot

If there is a bootconfig data in the tail of initrd/initramfs,
initrd image sanity check caused an error while decompression
stage as follows.

[    0.883882] Unpacking initramfs...
[    2.696429] Initramfs unpacking failed: invalid magic at start of compressed archive

This error will be ignored if CONFIG_BLK_DEV_RAM=n,
but CONFIG_BLK_DEV_RAM=y the kernel failed to mount rootfs
and causes a panic.

To fix this issue, shrink down the initrd_end for removing
tailing bootconfig data while boot the kernel.

Link: http://lkml.kernel.org/r/158788401014.24243.17424755854115077915.stgit@devnote2
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 7684b8582c24 ("bootconfig: Load boot config from the tail of initrd")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/init/main.c b/init/main.c
index a48617f..1a5da2c 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -257,6 +257,47 @@ static int __init loglevel(char *str)
 
 early_param("loglevel", loglevel);
 
+#ifdef CONFIG_BLK_DEV_INITRD
+static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+{
+       u32 size, csum;
+       char *data;
+       u32 *hdr;
+
+       if (!initrd_end)
+               return NULL;
+
+       data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
+       if (memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
+               return NULL;
+
+       hdr = (u32 *)(data - 8);
+       size = hdr[0];
+       csum = hdr[1];
+
+       data = ((void *)hdr) - size;
+       if ((unsigned long)data < initrd_start) {
+               pr_err("bootconfig size %d is greater than initrd size %ld\n",
+                       size, initrd_end - initrd_start);
+               return NULL;
+       }
+
+       /* Remove bootconfig from initramfs/initrd */
+       initrd_end = (unsigned long)data;
+       if (_size)
+               *_size = size;
+       if (_csum)
+               *_csum = csum;
+
+       return data;
+}
+#else
+static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+{
+       return NULL;
+}
+#endif
+
 #ifdef CONFIG_BOOT_CONFIG
 
 char xbc_namebuf[XBC_KEYLEN_MAX] __initdata;
@@ -357,9 +398,12 @@ static void __init setup_boot_config(const char *cmdline)
        int pos;
        u32 size, csum;
        char *data, *copy;
-       u32 *hdr;
        int ret;
 
+       data = get_boot_config_from_initrd(&size, &csum);
+       if (!data)
+               goto not_found;
+
        strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
        parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
                   bootconfig_params);
@@ -367,27 +411,12 @@ static void __init setup_boot_config(const char *cmdline)
        if (!bootconfig_found)
                return;
 
-       if (!initrd_end)
-               goto not_found;
-
-       data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
-       if (memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
-               goto not_found;
-
-       hdr = (u32 *)(data - 8);
-       size = hdr[0];
-       csum = hdr[1];
-
        if (size >= XBC_DATA_MAX) {
                pr_err("bootconfig size %d greater than max size %d\n",
                        size, XBC_DATA_MAX);
                return;
        }
 
-       data = ((void *)hdr) - size;
-       if ((unsigned long)data < initrd_start)
-               goto not_found;
-
        if (boot_config_checksum((unsigned char *)data, size) != csum) {
                pr_err("bootconfig checksum failed\n");
                return;
@@ -420,8 +449,14 @@ static void __init setup_boot_config(const char *cmdline)
 not_found:
        pr_err("'bootconfig' found on command line, but no bootconfig found\n");
 }
+
 #else
-#define setup_boot_config(cmdline)     do { } while (0)
+
+static void __init setup_boot_config(const char *cmdline)
+{
+       /* Remove bootconfig data from initrd */
+       get_boot_config_from_initrd(NULL, NULL);
+}
 
 static int __init warn_bootconfig(char *str)
 {