From 6a76f8c0ab19f215af2a3442870eeb5f0e81998d Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 11 Apr 2013 15:55:01 +0900 Subject: 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 Cc: Ingo Molnar Cc: Namhyung Kim Cc: stable@vger.kernel.org Signed-off-by: Namhyung Kim Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 10 +++++----- kernel/trace/trace_stack.c | 2 +- 2 files changed, 6 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 926ebfb74936..affc35d829cc 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -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, }; diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 42ca822fc701..83a8b5b7bd35 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -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, }; -- cgit v1.2.3 From 7f49ef69db6bbf756c0abca7e9b65b32e999eec8 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 12 Apr 2013 16:40:13 -0400 Subject: ftrace: Move ftrace_filter_lseek out of CONFIG_DYNAMIC_FTRACE section As ftrace_filter_lseek is now used with ftrace_pid_fops, it needs to be moved out of the #ifdef CONFIG_DYNAMIC_FTRACE section as the ftrace_pid_fops is defined when DYNAMIC_FTRACE is not. Cc: stable@vger.kernel.org Cc: Namhyung Kim Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 3 ++- kernel/trace/ftrace.c | 28 ++++++++++++++-------------- 2 files changed, 16 insertions(+), 15 deletions(-) (limited to 'kernel') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index eb3ce327b975..52da2a250795 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -396,7 +396,6 @@ 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_filter_lseek(struct file *file, loff_t offset, int whence); int ftrace_regex_release(struct inode *inode, struct file *file); void __init @@ -569,6 +568,8 @@ static inline int ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; } #endif /* CONFIG_DYNAMIC_FTRACE */ +loff_t ftrace_filter_lseek(struct file *file, loff_t offset, int whence); + /* totally disable ftrace - can not re-enable after this */ void ftrace_kill(void); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index affc35d829cc..2461ede45a8d 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1052,6 +1052,19 @@ static __init void ftrace_profile_debugfs(struct dentry *d_tracer) static struct pid * const ftrace_swapper_pid = &init_struct_pid; +loff_t +ftrace_filter_lseek(struct file *file, loff_t offset, int whence) +{ + loff_t ret; + + if (file->f_mode & FMODE_READ) + ret = seq_lseek(file, offset, whence); + else + file->f_pos = ret = 1; + + return ret; +} + #ifdef CONFIG_DYNAMIC_FTRACE #ifndef CONFIG_FTRACE_MCOUNT_RECORD @@ -2612,7 +2625,7 @@ static void ftrace_filter_reset(struct ftrace_hash *hash) * routine, you can use ftrace_filter_write() for the write * routine if @flag has FTRACE_ITER_FILTER set, or * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set. - * ftrace_regex_lseek() should be used as the lseek routine, and + * ftrace_filter_lseek() should be used as the lseek routine, and * release must call ftrace_regex_release(). */ int @@ -2696,19 +2709,6 @@ ftrace_notrace_open(struct inode *inode, struct file *file) inode, file); } -loff_t -ftrace_filter_lseek(struct file *file, loff_t offset, int whence) -{ - loff_t ret; - - if (file->f_mode & FMODE_READ) - ret = seq_lseek(file, offset, whence); - else - file->f_pos = ret = 1; - - return ret; -} - static int ftrace_match(char *str, char *regex, int len, int type) { int matched = 0; -- cgit v1.2.3