| From 6bbfa44116689469267f1a6e3d233b52114139d2 Mon Sep 17 00:00:00 2001 |
| From: Masami Hiramatsu <mhiramat@kernel.org> |
| Date: Wed, 1 Dec 2021 23:45:50 +0900 |
| Subject: kprobes: Limit max data_size of the kretprobe instances |
| |
| From: Masami Hiramatsu <mhiramat@kernel.org> |
| |
| commit 6bbfa44116689469267f1a6e3d233b52114139d2 upstream. |
| |
| The 'kprobe::data_size' is unsigned, thus it can not be negative. But if |
| user sets it enough big number (e.g. (size_t)-8), the result of 'data_size |
| + sizeof(struct kretprobe_instance)' becomes smaller than sizeof(struct |
| kretprobe_instance) or zero. In result, the kretprobe_instance are |
| allocated without enough memory, and kretprobe accesses outside of |
| allocated memory. |
| |
| To avoid this issue, introduce a max limitation of the |
| kretprobe::data_size. 4KB per instance should be OK. |
| |
| Link: https://lkml.kernel.org/r/163836995040.432120.10322772773821182925.stgit@devnote2 |
| |
| Cc: stable@vger.kernel.org |
| Fixes: f47cd9b553aa ("kprobes: kretprobe user entry-handler") |
| Reported-by: zhangyue <zhangyue1@kylinos.cn> |
| Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> |
| Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/linux/kprobes.h | 2 ++ |
| kernel/kprobes.c | 3 +++ |
| 2 files changed, 5 insertions(+) |
| |
| --- a/include/linux/kprobes.h |
| +++ b/include/linux/kprobes.h |
| @@ -192,6 +192,8 @@ struct kretprobe { |
| raw_spinlock_t lock; |
| }; |
| |
| +#define KRETPROBE_MAX_DATA_SIZE 4096 |
| + |
| struct kretprobe_instance { |
| struct hlist_node hlist; |
| struct kretprobe *rp; |
| --- a/kernel/kprobes.c |
| +++ b/kernel/kprobes.c |
| @@ -1899,6 +1899,9 @@ int register_kretprobe(struct kretprobe |
| } |
| } |
| |
| + if (rp->data_size > KRETPROBE_MAX_DATA_SIZE) |
| + return -E2BIG; |
| + |
| rp->kp.pre_handler = pre_handler_kretprobe; |
| rp->kp.post_handler = NULL; |
| rp->kp.fault_handler = NULL; |