| From: Geert Uytterhoeven <geert@linux-m68k.org> |
| Date: Thu, 16 May 2019 09:09:35 +0200 |
| Subject: cpu/speculation: Warn on unsupported mitigations= parameter |
| |
| commit 1bf72720281770162c87990697eae1ba2f1d917a upstream. |
| |
| Currently, if the user specifies an unsupported mitigation strategy on the |
| kernel command line, it will be ignored silently. The code will fall back |
| to the default strategy, possibly leaving the system more vulnerable than |
| expected. |
| |
| This may happen due to e.g. a simple typo, or, for a stable kernel release, |
| because not all mitigation strategies have been backported. |
| |
| Inform the user by printing a message. |
| |
| Fixes: 98af8452945c5565 ("cpu/speculation: Add 'mitigations=' cmdline option") |
| Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Jiri Kosina <jkosina@suse.cz> |
| Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Cc: Ben Hutchings <ben@decadent.org.uk> |
| Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.org |
| [bwh: Backported to 3.16: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| kernel/cpu.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/kernel/cpu.c |
| +++ b/kernel/cpu.c |
| @@ -804,6 +804,9 @@ static int __init mitigations_parse_cmdl |
| cpu_mitigations = CPU_MITIGATIONS_OFF; |
| else if (!strcmp(arg, "auto")) |
| cpu_mitigations = CPU_MITIGATIONS_AUTO; |
| + else |
| + pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", |
| + arg); |
| |
| return 0; |
| } |