ftrace: Check for successful allocation of hash

BugLink: https://bugs.launchpad.net/bugs/1843338
commit 5b0022dd32b7c2e15edf1827ba80aa1407edf9ff upstream.

In register_ftrace_function_probe(), we are not checking the return
value of alloc_and_copy_ftrace_hash(). The subsequent call to
ftrace_match_records() may end up dereferencing the same. Add a check to
ensure this doesn't happen.

Link: http://lkml.kernel.org/r/26e92574f25ad23e7cafa3cf5f7a819de1832cbe.1562249521.git.naveen.n.rao@linux.vnet.ibm.com
Cc: stable@vger.kernel.org
Fixes: 1ec3a81a0cf42 ("ftrace: Have each function probe use its own ftrace_ops")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0cc0e64fc5323b07e80574c93e6a132d556fe4a8..10709726ecf9bb366d660588c9e7589ae90e622a 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4358,6 +4358,11 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
        old_hash = *orig_hash;
        hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
 
+       if (!hash) {
+               ret = -ENOMEM;
+               goto out;
+       }
+
        ret = ftrace_match_records(hash, glob, strlen(glob));
 
        /* Nothing found? */