diff options
| author | Slava Pestov <slavapestov@google.com> | 2010-11-24 15:13:16 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-01-07 13:58:33 -0800 |
| commit | 3ee6c4cf578834e96653b821054cc7fa7246affc (patch) | |
| tree | ea09f47f3c2a7abcaf25a59a74cd31423737cce8 /kernel | |
| parent | ccbfc7594abfb470ab719da568e8bbd4265a888d (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>
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 9ec59f541156..7702f5aecd07 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2320,11 +2320,19 @@ 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, }; |