Re: [PATCH] x86/spectre: fix an error message

[Joe Perches]

On Wed, 2018-02-14 at 10:14 +0300, Dan Carpenter wrote:
> If i == ARRAY_SIZE(mitigation_options) then we accidentally print
> garbage from one space beyond the end of the mitigation_options[] array.
> 
> Fixes: 9005c6834c0f ("x86/spectre: Simplify spectre_v2 command line parsing")
> Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
> 
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index debcdda88560..acee4ebec04f 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -174,7 +174,7 @@ static enum spectre_v2_mitigation_cmd __init 
> spectre_v2_parse_cmdline(void)
>               }
>  
>               if (i >= ARRAY_SIZE(mitigation_options)) {
> -                     pr_err("unknown option (%s). Switching to AUTO 
> select\n", mitigation_options[i].option);
> +                     pr_err("unknown option (%s). Switching to AUTO 
> select\n", arg);
>                       return SPECTRE_V2_CMD_AUTO;
>               }
>       }

Should probably unindent this block too by
removing the else after the return

---
 arch/x86/kernel/cpu/bugs.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4acf16a76d1e..0af8245afb6c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -161,22 +161,21 @@ static enum spectre_v2_mitigation_cmd __init 
spectre_v2_parse_cmdline(void)
 
        if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
                return SPECTRE_V2_CMD_NONE;
-       else {
-               ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, 
sizeof(arg));
-               if (ret < 0)
-                       return SPECTRE_V2_CMD_AUTO;
-
-               for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
-                       if (!match_option(arg, ret, 
mitigation_options[i].option))
-                               continue;
-                       cmd = mitigation_options[i].cmd;
-                       break;
-               }
 
-               if (i >= ARRAY_SIZE(mitigation_options)) {
-                       pr_err("unknown option (%s). Switching to AUTO 
select\n", mitigation_options[i].option);
-                       return SPECTRE_V2_CMD_AUTO;
-               }
+       ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, 
sizeof(arg));
+       if (ret < 0)
+               return SPECTRE_V2_CMD_AUTO;
+
+       for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
+               if (!match_option(arg, ret, mitigation_options[i].option))
+                       continue;
+               cmd = mitigation_options[i].cmd;
+               break;
+       }
+
+       if (i >= ARRAY_SIZE(mitigation_options)) {
+               pr_err("unknown option (%s). Switching to AUTO select\n", arg);
+               return SPECTRE_V2_CMD_AUTO;
        }
 
        if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||