latencytop: fix kernel panic while reading latency proc file
Reading /proc/<pid>/latency or /proc/<pid>/task/<tid>/latency could cause NULL pointer dereference. In lstats_open(), get_proc_task() can return NULL, in which case the kernel will oops at lstats_show_proc() because m->private is NULL. When get_proc_task() returns NULL, the kernel should return -ENOENT. This can be reproduced by the following script. while : do date bash -c 'ls > ls.$$' & pid=$! cat /proc/$pid/latency & cat /proc/$pid/latency & cat /proc/$pid/latency & cat /proc/$pid/latency done Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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2d07b255c7
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ae0027869d
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@ -350,6 +350,8 @@ static int lstats_open(struct inode *inode, struct file *file)
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struct seq_file *m;
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struct task_struct *task = get_proc_task(inode);
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if (!task)
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return -ENOENT;
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ret = single_open(file, lstats_show_proc, NULL);
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if (!ret) {
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m = file->private_data;
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