4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Peter Zijlstra <[email protected]> commit 06ce6e9b6d6c09d4129c6e24a1314a395d816c10 upstream. > arch/x86/events/msr.c:178 msr_event_init() warn: potential spectre issue > 'msr' (local cap) Userspace controls @attr, sanitize cfg (attr->config) before using it to index an array. Reported-by: Dan Carpenter <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/cpu/perf_event_msr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/cpu/perf_event_msr.c +++ b/arch/x86/kernel/cpu/perf_event_msr.c @@ -1,4 +1,5 @@ #include <linux/perf_event.h> +#include <linux/nospec.h> enum perf_msr_id { PERF_MSR_TSC = 0, @@ -115,9 +116,6 @@ static int msr_event_init(struct perf_ev if (event->attr.type != event->pmu->type) return -ENOENT; - if (cfg >= PERF_MSR_EVENT_MAX) - return -EINVAL; - /* unsupported modes and filters */ if (event->attr.exclude_user || event->attr.exclude_kernel || @@ -128,6 +126,11 @@ static int msr_event_init(struct perf_ev event->attr.sample_period) /* no sampling */ return -EINVAL; + if (cfg >= PERF_MSR_EVENT_MAX) + return -EINVAL; + + cfg = array_index_nospec((unsigned long)cfg, PERF_MSR_EVENT_MAX); + if (!msr[cfg].attr) return -EINVAL;
