3.2.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Namhyung Kim <namhyung.kim@xxxxxxx> 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@xxxxxxxxxx Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Namhyung Kim <namhyung.kim@xxxxxxx> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> [bwh: Backported to 3.2: ftrace_regex_lseek() is static] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2316,7 +2316,7 @@ ftrace_notrace_open(struct inode *inode, } static 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; @@ -3134,7 +3134,7 @@ static const struct file_operations ftra .open = ftrace_filter_open, .read = seq_read, .write = ftrace_filter_write, - .llseek = ftrace_regex_lseek, + .llseek = ftrace_filter_lseek, .release = ftrace_regex_release, }; @@ -3142,7 +3142,7 @@ static const struct file_operations ftra .open = ftrace_notrace_open, .read = seq_read, .write = ftrace_notrace_write, - .llseek = ftrace_regex_lseek, + .llseek = ftrace_filter_lseek, .release = ftrace_regex_release, }; @@ -3350,8 +3350,8 @@ static const struct file_operations ftra .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 */ @@ -3843,7 +3843,7 @@ static const struct file_operations ftra .open = ftrace_pid_open, .write = ftrace_pid_write, .read = seq_read, - .llseek = seq_lseek, + .llseek = ftrace_filter_lseek, .release = ftrace_pid_release, }; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html