Messages in this thread Patch in this message | | | Date | Fri, 13 Nov 2020 08:29:30 -0500 | From | Steven Rostedt <> | Subject | [GIT PULL] bootconfig: Extend the magic check range to the preceding 3 bytes |
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Linus,
Fix alignment of bootconfig
GRUB may align the init ramdisk size to 4 bytes, the magic number at the end of the init ramdisk that denotes bootconfig is attached may not be at the exact end of the ramdisk. The kernel needs to check back at least 4 bytes.
Please pull the latest trace-v5.10-rc3 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-v5.10-rc3
Tag SHA1: e20c1d4f9314c2296b72a02f3e21c6116099f573 Head SHA1: 50b8a742850fce7293bed45753152c425f7e931b
Masami Hiramatsu (1): bootconfig: Extend the magic check range to the preceding 3 bytes
---- init/main.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --------------------------- commit 50b8a742850fce7293bed45753152c425f7e931b Author: Masami Hiramatsu <mhiramat@kernel.org> Date: Fri Nov 13 02:27:31 2020 +0900
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: 85c46b78da58 ("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>
diff --git a/init/main.c b/init/main.c index 130376ec10ba..20baced721ad 100644 --- a/init/main.c +++ b/init/main.c @@ -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)) - return NULL; + /* + * 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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