Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:
 "Misc fixlets"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix error return code
  ftrace: Fix strncpy() use, use strlcpy() instead of strncpy()
  perf: Fix strncpy() use, use strlcpy() instead of strncpy()
  perf: Fix strncpy() use, always make sure it's NUL terminated
  perf: Fix ring_buffer perf_output_space() boundary calculation
  perf/x86: Fix uninitialized pt_regs in intel_pmu_drain_bts_buffer()

6 files changed, 28 insertions, 11 deletions

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index b05a575d56f4..26830f3af0df 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -314,10 +314,11 @@ int intel_pmu_drain_bts_buffer(void)
         if (top <= at)
                 return 0;
 
+        memset(&regs, 0, sizeof(regs));
+
         ds->bts_index = ds->bts_buffer_base;
 
         perf_sample_data_init(&data, 0, event->hw.last_period);
-        regs.ip     = 0;
 
         /*
          * Prepare a generic sample, i.e. fill in the invariant fields.
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 59412d037eed..7e0962ed7f8a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4737,7 +4737,8 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
         } else {
                 if (arch_vma_name(mmap_event->vma)) {
                         name = strncpy(tmp, arch_vma_name(mmap_event->vma),
-                                       sizeof(tmp));
+                                       sizeof(tmp) - 1);
+                        tmp[sizeof(tmp) - 1] = '\0';
                         goto got_name;
                 }
 
@@ -5986,6 +5987,7 @@ skip_type:
         if (pmu->pmu_cpu_context)
                 goto got_cpu_context;
 
+        ret = -ENOMEM;
         pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
         if (!pmu->pmu_cpu_context)
                 goto free_dev;
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index d56a64c99a8b..eb675c4d59df 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -16,7 +16,7 @@ struct ring_buffer {
         int                             page_order;     /* allocation order  */
 #endif
         int                             nr_pages;       /* nr of data pages  */
-        int                             writable;       /* are we writable   */
+        int                             overwrite;      /* can overwrite itself */
 
         atomic_t                        poll;           /* POLL_ for wakeups */
 
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 23cb34ff3973..97fddb09762b 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -18,12 +18,24 @@
 static bool perf_output_space(struct ring_buffer *rb, unsigned long tail,
                               unsigned long offset, unsigned long head)
 {
-        unsigned long mask;
+        unsigned long sz = perf_data_size(rb);
+        unsigned long mask = sz - 1;
 
-        if (!rb->writable)
+        /*
+         * check if user-writable
+         * overwrite : over-write its own tail
+         * !overwrite: buffer possibly drops events.
+         */
+        if (rb->overwrite)
                 return true;
 
-        mask = perf_data_size(rb) - 1;
+        /*
+         * verify that payload is not bigger than buffer
+         * otherwise masking logic may fail to detect
+         * the "not enough space" condition
+         */
+        if ((head - offset) > sz)
+                return false;
 
         offset = (offset - tail) & mask;
         head   = (head   - tail) & mask;
@@ -212,7 +224,9 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
                 rb->watermark = max_size / 2;
 
         if (flags & RING_BUFFER_WRITABLE)
-                rb->writable = 1;
+                rb->overwrite = 0;
+        else
+                rb->overwrite = 1;
 
         atomic_set(&rb->refcount, 1);
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 2461ede45a8d..b3fde6d7b7fc 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3440,14 +3440,14 @@ static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;
 
 static int __init set_ftrace_notrace(char *str)
 {
-        strncpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
+        strlcpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
         return 1;
 }
 __setup("ftrace_notrace=", set_ftrace_notrace);
 
 static int __init set_ftrace_filter(char *str)
 {
-        strncpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
+        strlcpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
         return 1;
 }
 __setup("ftrace_filter=", set_ftrace_filter);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7ba7fc76f9eb..66338c4f7f4b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -132,7 +132,7 @@ static char *default_bootup_tracer;
 
 static int __init set_cmdline_ftrace(char *str)
 {
-        strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
+        strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
         default_bootup_tracer = bootup_tracer_buf;
         /* We are using ftrace early, expand it */
         ring_buffer_expanded = 1;
@@ -162,7 +162,7 @@ static char *trace_boot_options __initdata;
 
 static int __init set_trace_boot_options(char *str)
 {
-        strncpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
+        strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
         trace_boot_options = trace_boot_options_buf;
         return 0;
 }