tracing: Prevent bad count for tracing_cpumask_write

If a large count is provided, it will trigger a warning in bitmap_parse_user.
Also check zero for it.

Cc: stable@vger.kernel.org
Fixes: 9e01c1b74c953 ("cpumask: convert kernel trace functions")
Link: https://lore.kernel.org/20241216073238.2573704-1-lizhi.xu@windriver.com
Reported-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0aecfd34fb878546f3fd
Tested-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 957f941a08e743cc3bb8bc89597b950a6308b42e..f8aebcb01e62cf5e97f98fbeddd862bcf2d9cb9b 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5087,6 +5087,9 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
        cpumask_var_t tracing_cpumask_new;
        int err;
 
+       if (count == 0 || count > KMALLOC_MAX_SIZE)
+               return -EINVAL;
+
        if (!zalloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
                return -ENOMEM;