Re: [PATCH v2 1/8] x86/kaslr: Make command line handling safer

2020-07-28 Thread Kees Cook
On Mon, Jul 27, 2020 at 07:07:54PM -0400, Arvind Sankar wrote:
> Handle the possibility that the command line is NULL.
> 
> Replace open-coded strlen with a function call.
> 
> Signed-off-by: Arvind Sankar 

Reviewed-by: Kees Cook 

-- 
Kees Cook


[PATCH v2 1/8] x86/kaslr: Make command line handling safer

2020-07-27 Thread Arvind Sankar
Handle the possibility that the command line is NULL.

Replace open-coded strlen with a function call.

Signed-off-by: Arvind Sankar 
---
 arch/x86/boot/compressed/kaslr.c | 17 +
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index d7408af55738..a4af89646094 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -268,15 +268,19 @@ static void parse_gb_huge_pages(char *param, char *val)
 static void handle_mem_options(void)
 {
char *args = (char *)get_cmd_line_ptr();
-   size_t len = strlen((char *)args);
+   size_t len;
char *tmp_cmdline;
char *param, *val;
u64 mem_size;
 
+   if (!args)
+   return;
+
if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
!strstr(args, "hugepages"))
return;
 
+   len = strlen(args);
tmp_cmdline = malloc(len + 1);
if (!tmp_cmdline)
error("Failed to allocate space for tmp_cmdline");
@@ -399,8 +403,7 @@ static void mem_avoid_init(unsigned long input, unsigned 
long input_size,
 {
unsigned long init_size = boot_params->hdr.init_size;
u64 initrd_start, initrd_size;
-   u64 cmd_line, cmd_line_size;
-   char *ptr;
+   unsigned long cmd_line, cmd_line_size = 0;
 
/*
 * Avoid the region that is unsafe to overlap during
@@ -421,12 +424,10 @@ static void mem_avoid_init(unsigned long input, unsigned 
long input_size,
/* No need to set mapping for initrd, it will be handled in VO. */
 
/* Avoid kernel command line. */
-   cmd_line  = (u64)boot_params->ext_cmd_line_ptr << 32;
-   cmd_line |= boot_params->hdr.cmd_line_ptr;
+   cmd_line = get_cmd_line_ptr();
/* Calculate size of cmd_line. */
-   ptr = (char *)(unsigned long)cmd_line;
-   for (cmd_line_size = 0; ptr[cmd_line_size++];)
-   ;
+   if (cmd_line)
+   cmd_line_size = strlen((char *)cmd_line);
mem_avoid[MEM_AVOID_CMDLINE].start = cmd_line;
mem_avoid[MEM_AVOID_CMDLINE].size = cmd_line_size;
add_identity_map(mem_avoid[MEM_AVOID_CMDLINE].start,
-- 
2.26.2