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@dev...
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 @@ -154,6 +154,8 @@ struct kretprobe { struct kretprobe_holder *rph; };
+#define KRETPROBE_MAX_DATA_SIZE 4096 + struct kretprobe_instance { union { struct freelist_node freelist; --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2006,6 +2006,9 @@ 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;