[PATCH] debugfs: write_file_bool() - ensure strtobool() operates on valid data

[Mathias Krause]

In case, userland writes an empty string to a bool debugfs file, buf[]
will still be uninitialized when being passed to strtobool() making the
outcome of that function purely random.

Fix this by always zero-terminating the buffer.

Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
---
 fs/debugfs/file.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index c5ca6ae..b15a1c5 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -431,6 +431,7 @@ static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 	if (copy_from_user(buf, user_buf, buf_size))
 		return -EFAULT;
 
+	buf[buf_size] = '\0';
 	if (strtobool(buf, &bv) == 0)
 		*val = bv;
 
-- 
1.7.10.4

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