linux-kernel - Re: [offlist] uprobe: checking probe event include directory

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Date:	Wed, 18 Jul 2012 19:38:27 +0800
From:	Jovi Zhang <bookjovi@...il.com>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [offlist] uprobe: checking probe event include directory

On Wed, Jul 18, 2012 at 7:07 PM, Srikar Dronamraju
<srikar@...ux.vnet.ibm.com> wrote:
> The patch looks good,
>
> Can you modify the description a bit. However you are free to ignore
> these comments. After knowing your response,  I will ack the patch.
>
> I would probably put this as:
>
> The subject could be
> tracing: Verify target file before registering a uprobe event
>
> Description:
> Without this patch, we can register a uprobe event for a directory.
> Enabling such a uprobe event would anyway fail.
>
> Example:
>
> $ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events
>
> However directories cannot be valid targets for uprobe.
> Hence verify if the target is a regular file during the probe
> registration.

Thanks srikar, your description is more clear than mine.


>From fd5077196038cc271e2116e1fca359a0011e1669 Mon Sep 17 00:00:00 2001
From: Jovi Zhang <bookjovi@...il.com>
Date: Wed, 18 Jul 2012 18:16:44 +0800
Subject: [PATCH] tracing: Verify target file before registering a uprobe
 event

Without this patch, we can register a uprobe event for a directory.
Enabling such a uprobe event would anyway fail.

Example:
$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe.
Hence verify if the target is a regular file during the probe
registration.

Signed-off-by: Jovi Zhang <bookjovi@...il.com>
Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
 kernel/trace/trace_uprobe.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 85158fa..3b5f646 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -259,6 +259,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;

 	inode = igrab(path.dentry->d_inode);
+	 if (!S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) {
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}

 	argc -= 2;
 	argv += 2;
@@ -358,7 +362,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);

-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");

 	return ret;
 }
-- 
1.7.9.7
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