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: 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>

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index be7a49f437ea398304fc3d424b63e15af6ec8af7..019444c04f58b27342f9dd390a5102ba4cb1cae6 100644 (file)
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -193,6 +193,8 @@ struct kretprobe {
        raw_spinlock_t lock;
 };
 
+#define KRETPROBE_MAX_DATA_SIZE        4096
+
 struct kretprobe_instance {
        struct hlist_node hlist;
        struct kretprobe *rp;

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d752c1df8f3fdec35a4ac5150fe5bf1450758d1a..4f918dd28fb7bc141dec98f332cd727678c51ecc 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -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.post_handler = NULL;
        rp->kp.fault_handler = NULL;