Commit 2f16a429 authored Dec 01, 2021 by Masami Hiramatsu Committed by Greg Kroah-Hartman Dec 08, 2021

kprobes: Limit max data_size of the kretprobe instances

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: f47cd9b5 ("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>

parent 95d61f9f

include/linux/kprobes.h

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -193,6 +193,8 @@ struct kretprobe {
	raw_spinlock_t lock;		raw_spinlock_t lock;
	};		};

			#define KRETPROBE_MAX_DATA_SIZE 4096

	struct kretprobe_instance {		struct kretprobe_instance {
	struct hlist_node hlist;		struct hlist_node hlist;
	struct kretprobe *rp;		struct kretprobe *rp;

kernel/kprobes.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -2004,6 +2004,9 @@ int register_kretprobe(struct kretprobe *rp)
	}		}
	}		}

			if (rp->data_size > KRETPROBE_MAX_DATA_SIZE)
			return -E2BIG;

	rp->kp.pre_handler = pre_handler_kretprobe;		rp->kp.pre_handler = pre_handler_kretprobe;
	rp->kp.post_handler = NULL;		rp->kp.post_handler = NULL;
	rp->kp.fault_handler = NULL;		rp->kp.fault_handler = NULL;