From 6fcca0fa48118e6d63733eb4644c6cd880c15b8f Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Mon, 3 Feb 2020 13:22:16 -0800 Subject: [PATCH] sched/psi: Fix OOB write when writing 0 bytes to PSI files Issuing write() with count parameter set to 0 on any file under /proc/pressure/ will cause an OOB write because of the access to buf[buf_size-1] when NUL-termination is performed. Fix this by checking for buf_size to be non-zero. Signed-off-by: Suren Baghdasaryan Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Johannes Weiner Link: https://lkml.kernel.org/r/20200203212216.7076-1-surenb@google.com --- kernel/sched/psi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index db7b50bba3f1..38ccd49b9bf6 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1199,6 +1199,9 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf, if (static_branch_likely(&psi_disabled)) return -EOPNOTSUPP; + if (!nbytes) + return -EINVAL; + buf_size = min(nbytes, sizeof(buf)); if (copy_from_user(buf, user_buf, buf_size)) return -EFAULT;