trace_kprobes: Fix a memory leak bug and check kstrdup() return value

Fix a memory leak case in create_trace_probe(). When an argument
is too long (> MAX_ARGSTR_LEN), it just jumps to error path. In
that case tp->args[i].name is not released.
This also fixes a bug to check kstrdup()'s return value.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091201001919.10235.56455.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 72d0c65c8676b8bc048c6c865c202335aa492a89..aff5f80b59b8785cffe69091aa48a225d700add8 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -483,7 +483,8 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
        return ret;
 }
 
-static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+/* Recursive argument parser */
+static int __parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 {
        int ret = 0;
        unsigned long param;
@@ -543,7 +544,7 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
                        if (!id)
                                return -ENOMEM;
                        id->offset = offset;
-                       ret = parse_probe_arg(arg, &id->orig, is_return);
+                       ret = __parse_probe_arg(arg, &id->orig, is_return);
                        if (ret)
                                kfree(id);
                        else {
@@ -560,6 +561,16 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
        return ret;
 }
 
+/* String length checking wrapper */
+static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+{
+       if (strlen(arg) > MAX_ARGSTR_LEN) {
+               pr_info("Argument is too long.: %s\n",  arg);
+               return -ENOSPC;
+       }
+       return __parse_probe_arg(arg, ff, is_return);
+}
+
 /* Return 1 if name is reserved or already used by another argument */
 static int conflict_field_name(const char *name,
                               struct probe_arg *args, int narg)
@@ -698,13 +709,14 @@ static int create_trace_probe(int argc, char **argv)
                }
 
                tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
-
-               /* Parse fetch argument */
-               if (strlen(arg) > MAX_ARGSTR_LEN) {
-                       pr_info("Argument%d(%s) is too long.\n", i, arg);
-                       ret = -ENOSPC;
+               if (!tp->args[i].name) {
+                       pr_info("Failed to allocate argument%d name '%s'.\n",
+                               i, argv[i]);
+                       ret = -ENOMEM;
                        goto error;
                }
+
+               /* Parse fetch argument */
                ret = parse_probe_arg(arg, &tp->args[i].fetch, is_return);
                if (ret) {
                        pr_info("Parse error at argument%d. (%d)\n", i, ret);