Messages in this thread Patch in this message | | | From | Slava Pestov <> | Subject | [PATCH] ftrace: Fix panic when lseek() called on "trace" opened for writing | Date | Wed, 24 Nov 2010 15:13:16 -0800 |
| |
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.
This patch is for Linux 2.6.36.1.
Signed-Off-By: Slava Pestov <slavapestov@google.com> ---
Change-Id: Iaabc50d84fb541c04e3efabd4788cebadbadbb4c --- 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 9ec59f5..7702f5a 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, }; -- 1.7.3.1
| |