diff options
author | Slava Pestov <slavapestov@google.com> | 2010-11-24 15:13:16 -0800 |
---|---|---|
committer | AK <andi@firstfloor.org> | 2011-02-06 11:03:43 -0800 |
commit | be5057e86f2813ec2a16bf0878d0d2cc6dae5e81 (patch) | |
tree | 86daff5bfce672c48ef1e8fb4bcadf1d3561b7cc /kernel | |
parent | c3a057e54f2cb3efc797633d7d7102db90beed50 (diff) |
tracing: Fix panic when lseek() called on "trace" opened for writing
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>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/trace/trace.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 086d36316805..755d3ee9d453 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2382,11 +2382,19 @@ tracing_write_stub(struct file *filp, const char __user *ubuf, 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, }; |