kretprobe: Avoid re-registration of the same kretprobe earlier

Our system encountered a re-init error when re-registering same kretprobe,
where the kretprobe_instance in rp->free_instances is illegally accessed
after re-init.

Implementation to avoid re-registration has been introduced for kprobe
before, but lags for register_kretprobe(). We must check if kprobe has
been re-registered before re-initializing kretprobe, otherwise it will
destroy the data struct of kretprobe registered, which can lead to memory
leak, system crash, also some unexpected behaviors.

We use check_kprobe_rereg() to check if kprobe has been re-registered
before running register_kretprobe()'s body, for giving a warning message
and terminate registration process.

Link: https://lkml.kernel.org/r/20210128124427.2031088-1-bobo.shaobowang@huawei.com
Cc: stable@vger.kernel.org
Fixes: 1f0ab40976460 ("kprobes: Prevent re-registration of the same kprobe")
[ The above commit should have been done for kretprobes too ]
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1a5bc321e0a5ee99caac2fe09e5429349285942f..d5a3eb74a6574aade1fb23c3959a7ababee96d66 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1994,6 +1994,10 @@ int register_kretprobe(struct kretprobe *rp)
        if (ret)
                return ret;
 
+       /* If only rp->kp.addr is specified, check reregistering kprobes */
+       if (rp->kp.addr && check_kprobe_rereg(&rp->kp))
+               return -EINVAL;
+
        if (kretprobe_blacklist_size) {
                addr = kprobe_addr(&rp->kp);
                if (IS_ERR(addr))