LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: ananth@in.ibm.com, David Miller <davem@davemloft.net>,
	mhiramat@redhat.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: [PATCH] kprobes: disable preempt for module_text_address()
Date: Tue, 04 Nov 2008 13:56:21 +0800	[thread overview]
Message-ID: <490FE405.1000105@cn.fujitsu.com> (raw)


__register_kprobe() may be preempted after module_text_address()
but before try_module_get(), and in this interval the module may be
unloaded and try_module_get(probed_mod) will access to invalid address.
this patch uses preempt_disable() to protect it.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 8b57a25..8238ec5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -622,6 +622,7 @@ static int __kprobes __register_kprobe(struct kprobe *p,
 	/*
 	 * Check if are we probing a module.
 	 */
+	preempt_disable();
 	probed_mod = module_text_address((unsigned long) p->addr);
 	if (probed_mod) {
 		struct module *calling_mod = module_text_address(called_from);
@@ -631,12 +632,15 @@ static int __kprobes __register_kprobe(struct kprobe *p,
 		 * unloading of self probing modules.
 		 */
 		if (calling_mod && calling_mod != probed_mod) {
-			if (unlikely(!try_module_get(probed_mod)))
+			if (unlikely(!try_module_get(probed_mod))) {
+				preempt_enable();
 				return -EINVAL;
+			}
 			p->mod_refcounted = 1;
 		} else
 			probed_mod = NULL;
 	}
+	preempt_enable();
 
 	p->nmissed = 0;
 	INIT_LIST_HEAD(&p->list);




             reply	other threads:[~2008-11-04  6:01 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-04  5:56 Lai Jiangshan [this message]
2008-11-04 14:28 ` Ananth N Mavinakayanahalli
2008-11-05  0:53   ` Lai Jiangshan
2008-11-05  1:27 ` Masami Hiramatsu
2008-11-05  1:47   ` Lai Jiangshan
2008-11-05 19:30     ` Hiroshi Shimamoto
2008-11-05 21:40     ` Masami Hiramatsu
2008-11-05 22:46       ` Hiroshi Shimamoto
2008-11-05 23:07         ` Masami Hiramatsu
2008-11-06  0:06           ` [PATCH] kprobes: bugfix: try_module_get even if calling_mod is NULL Masami Hiramatsu
2008-11-07  1:00             ` Andrew Morton
2008-11-07  2:28               ` Masami Hiramatsu
2008-11-07  2:54                 ` Andrew Morton
2008-11-07  4:46                   ` Ananth N Mavinakayanahalli
2008-11-06  1:06       ` [PATCH] kprobes: disable preempt for module_text_address() Lai Jiangshan
2008-11-06 15:37         ` [PATCH] kprobes: disable preempt for module_text_address() and kernel_text_address() Masami Hiramatsu
2008-11-07  0:32           ` Lai Jiangshan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=490FE405.1000105@cn.fujitsu.com \
    --to=laijs@cn.fujitsu.com \
    --cc=akpm@linux-foundation.org \
    --cc=ananth@in.ibm.com \
    --cc=davem@davemloft.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhiramat@redhat.com \
    --subject='Re: [PATCH] kprobes: disable preempt for module_text_address()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).