Messages in this thread Patch in this message | | | Date | Thu, 02 Dec 2010 13:46:13 -0500 | From | Steven Rostedt <> | Subject | [PATCH 1/3] tracing: Fix panic when lseek() called on "trace" opened for writing |
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From: Slava Pestov <slavapestov@google.com>
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.
Cc: <stable@kernel.org> 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> --- 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 ee6a733..21db0de 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2339,11 +2339,19 @@ 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, }; -- 1.7.2.3
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