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: Sam Sun <samsun1006219@gmail.com>
Closes: https://lkml.kernel.org/r/CAEkJfYNDspuGxYx5kym8Lvp--D36CMDUErg4rxfWFJuPbbji8g@mail.gmail.com
Fixes: bd03a3e4c9
("TOMOYO: Add policy namespace support.")
Cc: <stable@vger.kernel.org> # Linux 3.1+
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -2649,13 +2649,14 @@ ssize_t tomoyo_write_control(struct tomoyo_io_buffer *head,
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{
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int error = buffer_len;
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size_t avail_len = buffer_len;
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char *cp0 = head->write_buf;
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char *cp0;
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int idx;
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if (!head->write)
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return -EINVAL;
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if (mutex_lock_interruptible(&head->io_sem))
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return -EINTR;
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cp0 = head->write_buf;
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head->read_user_buf_avail = 0;
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idx = tomoyo_read_lock();
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/* Read a line and dispatch it to the policy handler. */
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