Commit 6a76f8c0 authored by Namhyung Kim's avatar Namhyung Kim Committed by Steven Rostedt

tracing: Fix possible NULL pointer dereferences

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

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 83e03b3f
......@@ -396,7 +396,7 @@ ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos);
ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos);
loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int whence);
loff_t ftrace_filter_lseek(struct file *file, loff_t offset, int whence);
int ftrace_regex_release(struct inode *inode, struct file *file);
void __init
......
......@@ -2697,7 +2697,7 @@ ftrace_notrace_open(struct inode *inode, struct file *file)
}
loff_t
ftrace_regex_lseek(struct file *file, loff_t offset, int whence)
ftrace_filter_lseek(struct file *file, loff_t offset, int whence)
{
loff_t ret;
......@@ -3570,7 +3570,7 @@ static const struct file_operations ftrace_filter_fops = {
.open = ftrace_filter_open,
.read = seq_read,
.write = ftrace_filter_write,
.llseek = ftrace_regex_lseek,
.llseek = ftrace_filter_lseek,
.release = ftrace_regex_release,
};
......@@ -3578,7 +3578,7 @@ static const struct file_operations ftrace_notrace_fops = {
.open = ftrace_notrace_open,
.read = seq_read,
.write = ftrace_notrace_write,
.llseek = ftrace_regex_lseek,
.llseek = ftrace_filter_lseek,
.release = ftrace_regex_release,
};
......@@ -3783,8 +3783,8 @@ static const struct file_operations ftrace_graph_fops = {
.open = ftrace_graph_open,
.read = seq_read,
.write = ftrace_graph_write,
.llseek = ftrace_filter_lseek,
.release = ftrace_graph_release,
.llseek = seq_lseek,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
......@@ -4439,7 +4439,7 @@ static const struct file_operations ftrace_pid_fops = {
.open = ftrace_pid_open,
.write = ftrace_pid_write,
.read = seq_read,
.llseek = seq_lseek,
.llseek = ftrace_filter_lseek,
.release = ftrace_pid_release,
};
......
......@@ -322,7 +322,7 @@ 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,
};
......
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