Commit 2f03fc34 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Linus Torvalds
Browse files

tomoyo: fix UAF write bug in tomoyo_write_control() 



Since tomoyo_write_control() updates head->write_buf when write()
of long lines is requested, we need to fetch head->write_buf after
head->io_sem is held.  Otherwise, concurrent write() requests can
cause use-after-free-write and double-free problems.

Reported-by: default avatarSam Sun <samsun1006219@gmail.com>
Closes: https://lkml.kernel.org/r/CAEkJfYNDspuGxYx5kym8Lvp--D36CMDUErg4rxfWFJuPbbji8g@mail.gmail.com


Fixes: bd03a3e4 ("TOMOYO: Add policy namespace support.")
Cc:  <stable@vger.kernel.org> # Linux 3.1+
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 87adedeb

security/tomoyo/common.c

+2 −1
Original line number Diff line number Diff line
@@ -2649,13 +2649,14 @@ ssize_t tomoyo_write_control(struct tomoyo_io_buffer *head, 
{

	int error = buffer_len;

	size_t avail_len = buffer_len;

	char *cp0 = head->write_buf;

	char *cp0;

	int idx;



	if (!head->write)

		return -EINVAL;

	if (mutex_lock_interruptible(&head->io_sem))

		return -EINTR;

	cp0 = head->write_buf;

	head->read_user_buf_avail = 0;

	idx = tomoyo_read_lock();

	/* Read a line and dispatch it to the policy handler. */