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x86/kaslr: Make command line handling safer

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Handle the possibility that the command line is NULL.

Replace open-coded strlen with a function call.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200727230801.3468620-2-nivedita@alum.mit.edu
This commit is contained in:
Arvind Sankar 2020-07-27 19:07:54 -04:00 committed by Ingo Molnar
parent 92ed301919
commit 709709ac64
1 changed files with 14 additions and 12 deletions
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26
arch/x86/boot/compressed/kaslr.c
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@ -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;
/*
* Avoid the region that is unsafe to overlap during
@ -421,16 +424,15 @@ 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++];)
;
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,
mem_avoid[MEM_AVOID_CMDLINE].size);
if (cmd_line) {
cmd_line_size = strlen((char *)cmd_line) + 1;
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,
mem_avoid[MEM_AVOID_CMDLINE].size);
}
/* Avoid boot parameters. */
mem_avoid[MEM_AVOID_BOOTPARAMS].start = (unsigned long)boot_params;