Commit 50b8a742 authored Nov 13, 2020 by Masami Hiramatsu Committed by Steven Rostedt (VMware) Nov 12, 2020

bootconfig: Extend the magic check range to the preceding 3 bytes

Since Grub may align the size of initrd to 4 if user pass
initrd from cpio, we have to check the preceding 3 bytes as well.

Link: https://lkml.kernel.org/r/160520205132.303174.4876760192433315429.stgit@devnote2



Cc: stable@vger.kernel.org
Fixes: 85c46b78 ("bootconfig: Add bootconfig magic word for indicating bootconfig explicitly")
Reported-by: Chen Yu <yu.chen.surf@gmail.com>
Tested-by: Chen Yu <yu.chen.surf@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 645f224e

init/main.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -269,14 +269,24 @@ static void * __init get_boot_config_from_initrd(u32 _size, u32 _csum)
		u32 size, csum;
		char *data;
		u32 *hdr;
		int i;

		if (!initrd_end)
		return NULL;

		data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
		if (memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
		/*
		* Since Grub may align the size of initrd to 4, we must
		* check the preceding 3 bytes as well.
		*/
		for (i = 0; i < 4; i++) {
		if (!memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
		goto found;
		data--;
		}
		return NULL;

		found:
		hdr = (u32 *)(data - 8);
		size = hdr[0];
		csum = hdr[1];

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