From: Masami Hiramatsu Date: Tue, 6 Jan 2009 22:41:46 +0000 (-0800) Subject: kprobes: bugfix: try_module_get even if calling_mod is NULL X-Git-Tag: v2.6.29-rc1~317 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=bc2f70151fe7a117dbe8347edc5a877e749572a3;p=~shefty%2Frdma-dev.git kprobes: bugfix: try_module_get even if calling_mod is NULL When someone called register_*probe() from kernel-core code(not from module) and that probes a kernel module, users can remove the probed module because kprobe doesn't increment reference counter of the module. (on the other hand, if the kernel-module calls register_*probe, kprobe increments refcount of the probed module.) Currently, we have no register_*probe() calling from kernel-core(except smoke-test, but the smoke-test doesn't probe module), so there is no real bugs. But the logic is wrong(or not fair) and it can causes a problem when someone might want to probe module from kernel. After this patch is applied, even if someone put register_*probe() call in the kernel-core code, it increments the reference counter of the probed module, and it prevents user to remove the module until stopping probing it. Signed-off-by: Masami Hiramatsu Cc: Lai Jiangshan Cc: Ananth N Mavinakayanahalli Cc: Hiroshi Shimamoto Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9f8a3f25259..3afd354c46f 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -634,7 +634,7 @@ static int __kprobes __register_kprobe(struct kprobe *p, * avoid incrementing the module refcount, so as to allow * unloading of self probing modules. */ - if (calling_mod && calling_mod != probed_mod) { + if (calling_mod != probed_mod) { if (unlikely(!try_module_get(probed_mod))) { preempt_enable(); return -EINVAL;