Messages in this thread | | | Subject | Re: [RFC PATCH 2/2] x86/cmdline: Use strscpy to initialize boot_command_line | From | Randy Dunlap <> | Date | Sat, 5 Sep 2020 15:59:04 -0700 |
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On 9/5/20 3:23 PM, Arvind Sankar wrote: > The x86 boot protocol requires the kernel command line to be a > NUL-terminated string of length at most COMMAND_LINE_SIZE (including the > terminating NUL). In case the bootloader messed up and the command line > is too long (hence not NUL-terminated), use strscpy to copy the command > line into boot_command_line. This ensures that boot_command_line is > NUL-terminated, and it also avoids accessing beyond the actual end of > the command line if it was properly NUL-terminated. > > Note that setup_arch() will already force command_line to be > NUL-terminated by using strlcpy(), as well as boot_command_line if a > builtin command line is configured. If boot_command_line was not > initially NUL-terminated, the strlen() inside of strlcpy()/strlcat() > will run beyond boot_command_line, but this is almost certainly > harmless in practice. > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Hi, Just for my enlightenment, what would be wrong with:
(which is done in arch/m68/kernel/setup_no.c)
> --- > arch/x86/kernel/head64.c | 2 +- > arch/x86/kernel/head_32.S | 11 +++++------ > 2 files changed, 6 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index cbb71c1b574f..740dd05b9462 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -410,7 +410,7 @@ static void __init copy_bootdata(char *real_mode_data) > cmd_line_ptr = get_cmd_line_ptr(); > if (cmd_line_ptr) { > command_line = __va(cmd_line_ptr); > memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE); > + boot_command_line[COMMAND_LINE_SIZE - 1] = 0; > } > > /*
thanks. -- ~Randy
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