blktrace: pass the right pointer to kfree()

Impact: fix kfree crash with non-standard act_mask string

If passing a string with leading white spaces to strstrip(),
the returned ptr != the original ptr.

This bug was introduced by me.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49DD694C.8020902@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index b32ff446c3fb3c1d4e88829ac46a9e0adc705031..921ef5d1f0ba95e7497faa55afb293c50ae7ee47 100644 (file)
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1377,12 +1377,12 @@ static int blk_trace_str2mask(const char *str)
 {
        int i;
        int mask = 0;
-       char *s, *token;
+       char *buf, *s, *token;
 
-       s = kstrdup(str, GFP_KERNEL);
-       if (s == NULL)
+       buf = kstrdup(str, GFP_KERNEL);
+       if (buf == NULL)
                return -ENOMEM;
-       s = strstrip(s);
+       s = strstrip(buf);
 
        while (1) {
                token = strsep(&s, ",");
@@ -1403,7 +1403,7 @@ static int blk_trace_str2mask(const char *str)
                        break;
                }
        }
-       kfree(s);
+       kfree(buf);
 
        return mask;
 }