From 3a22cc7f184b77731816e55662cd12f0c3d24d56 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Fri, 7 Jun 2013 17:01:16 +0800 Subject: tracing: Fix possible NULL pointer dereferences commit 6a76f8c0ab19f215af2a3442870eeb5f0e81998d upstream. Currently set_ftrace_pid and set_graph_function files use seq_lseek for their fops. However seq_open() is called only for FMODE_READ in the fops->open() so that if an user tries to seek one of those file when she open it for writing, it sees NULL seq_file and then panic. It can be easily reproduced with following command: $ cd /sys/kernel/debug/tracing $ echo 1234 | sudo tee -a set_ftrace_pid In this example, GNU coreutils' tee opens the file with fopen(, "a") and then the fopen() internally calls lseek(). Link: http://lkml.kernel.org/r/1365663302-2170-1-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Namhyung Kim Signed-off-by: Steven Rostedt [ lizf: adjust context ] Signed-off-by: Li Zefan Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_stack.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/trace_stack.c') diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index c70f6bfbb732..8298997c2486 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -384,7 +384,7 @@ static const struct file_operations stack_trace_filter_fops = { .open = stack_trace_filter_open, .read = seq_read, .write = ftrace_filter_write, - .llseek = ftrace_regex_lseek, + .llseek = ftrace_filter_lseek, .release = ftrace_regex_release, }; -- cgit v1.2.3