From: Wang ShaoBo bobo.shaobowang@huawei.com

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.co...

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 --- kernel/kprobes.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 1a5bc321e0a5..d5a3eb74a657 100644 --- 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))