Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756550Ab0KXXNY (ORCPT ); Wed, 24 Nov 2010 18:13:24 -0500 Received: from smtp-out.google.com ([74.125.121.35]:2602 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753612Ab0KXXNV (ORCPT ); Wed, 24 Nov 2010 18:13:21 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer; b=ZzY4w5c/A9cBw5qZnpN2tT5oexnPs1+frThXAv1lbI66lrrV08uW7F+UJqRIifJ4y fX7e0qnKpEdlNZY9p6Bqw== From: Slava Pestov To: linux-kernel@vger.kernel.org Cc: dhsharp@google.com, mrubin@google.com, Slava Pestov Subject: [PATCH] ftrace: Fix panic when lseek() called on "trace" opened for writing Date: Wed, 24 Nov 2010 15:13:16 -0800 Message-Id: <1290640396-24179-1-git-send-email-slavapestov@google.com> X-Mailer: git-send-email 1.7.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1513 Lines: 50 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 --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/