TOMOYO: Fix infinite loop bug when reading /sys/kernel/security/tomoyo/audit

In tomoyo_flush(), head->r.w[0] holds pointer to string data to be printed.
But head->r.w[0] was updated only when the string data was partially
printed (because head->r.w[0] will be updated by head->r.w[1] later if
completely printed). However, regarding /sys/kernel/security/tomoyo/query ,
an additional '\0' is printed after the string data was completely printed.
But if free space for read buffer became 0 before printing the additional '\0',
tomoyo_flush() was returning without updating head->r.w[0]. As a result,
tomoyo_flush() forever reprints already printed string data.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 2b7b1a123600..a0d09e56874b 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -108,10 +108,9 @@ static bool tomoyo_flush(struct tomoyo_io_buffer *head)
                         head->read_user_buf += len;
                         w += len;
                 }
-                if (*w) {
-                        head->r.w[0] = w;
+                head->r.w[0] = w;
+                if (*w)
                         return false;
-                }
                 /* Add '\0' for query. */
                 if (head->poll) {
                         if (!head->read_user_buf_avail ||