[054/126] tracing: Fix possible NULL pointer dereferences

Steven Rostedt
2013-05-07T04:27:11Z

[-- Attachment #1: 0054-tracing-Fix-possible-NULL-pointer-dereferences.patch --]
[-- Type: text/plain, Size: 3804 bytes --]

3.6.11.3 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Namhyung Kim <namhyung.kim@lge.com>

[ Upstream commit 6a76f8c0ab19f215af2a3442870eeb5f0e81998d ]

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: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ftrace.h | 2 +-
kernel/trace/ftrace.c | 10 +++++-----
kernel/trace/trace_stack.c | 2 +-
3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 55e6d63..6ce7928 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -305,7 +305,7 @@ 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 origin);
+loff_t ftrace_filter_lseek(struct file *file, loff_t offset, int origin);
int ftrace_regex_release(struct inode *inode, struct file *file);

void __init
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a1dd715..ae08e1e 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2594,7 +2594,7 @@ ftrace_notrace_open(struct inode *inode, struct file *file)
}

loff_t
-ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
+ftrace_filter_lseek(struct file *file, loff_t offset, int origin)
{
loff_t ret;

@@ -3413,7 +3413,7 @@ 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,
};

@@ -3421,7 +3421,7 @@ 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,
};

@@ -3626,8 +3626,8 @@ 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 */

@@ -4236,7 +4236,7 @@ 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,
};

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index d4545f4..aa4270a 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -324,7 +324,7 @@ 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,
};

--
1.7.10.4