lkml.org 
[lkml]   [2011]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] [88/139] tracing: Fix panic when lseek() called on "trace" opened for writing
Date
2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Slava Pestov <slavapestov@google.com>

commit 364829b1263b44aa60383824e4c1289d83d78ca7 upstream.

The file_ops struct for the "trace" special file defined llseek as seq_lseek().
However, if the file was opened for writing only, seq_open() was not called,
and the seek would dereference a null pointer, file->private_data.

This patch introduces a new wrapper for seq_lseek() which checks if the file
descriptor is opened for reading first. If not, it does nothing.

Signed-off-by: Slava Pestov <slavapestov@google.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <1290640396-24179-1-git-send-email-slavapestov@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/trace/trace.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

Index: linux-2.6.35.y/kernel/trace/trace.c
===================================================================
--- linux-2.6.35.y.orig/kernel/trace/trace.c
+++ linux-2.6.35.y/kernel/trace/trace.c
@@ -2382,11 +2382,19 @@ tracing_write_stub(struct file *filp, co
return count;
}

+static loff_t tracing_seek(struct file *file, loff_t offset, int origin)
+{
+ if (file->f_mode & FMODE_READ)
+ return seq_lseek(file, offset, origin);
+ else
+ return 0;
+}
+
static const struct file_operations tracing_fops = {
.open = tracing_open,
.read = seq_read,
.write = tracing_write_stub,
- .llseek = seq_lseek,
+ .llseek = tracing_seek,
.release = tracing_release,
};


\
 
 \ /
  Last update: 2011-02-02 01:57    [W:0.305 / U:4.116 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site