profile: fix stats and data leakage

If the kernel is large or the profiling step small, /proc/profile
leaks data and readprofile shows silly stats, until readprofile -r
has reset the buffer: clear the prof_buffer when it is vmalloc()ed.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/profile.c b/kernel/profile.c
index a55d3a3..dfadc5b 100644 (file)
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -127,8 +127,10 @@ int __ref profile_init(void)
                return 0;
 
        prof_buffer = vmalloc(buffer_bytes);
-       if (prof_buffer)
+       if (prof_buffer) {
+               memset(prof_buffer, 0, buffer_bytes);
                return 0;
+       }
 
        free_cpumask_var(prof_cpu_mask);
        return -ENOMEM;