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authorSlava Pestov <slavapestov@google.com>2010-11-24 15:13:16 -0800
committerSteven Rostedt <rostedt@goodmis.org>2010-11-30 12:18:17 -0500
commit364829b1263b44aa60383824e4c1289d83d78ca7 (patch)
treedaaaf4cecd56ff9f3f9a2eadc69d0cc4f361c607 /kernel
parent60e677373be9c0bf7c9a22937601d5a40e51c042 (diff)
tracing: Fix panic when lseek() called on "trace" opened for writing
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ee6a7339cf0e..21db0deb5c7d 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,
};