5.10-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit 2f03fc340cac9ea1dc63cbf8c93dd2eb0f227815 upstream.
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--D36CMDUErg4rxfWFJuPbbji8... Fixes: bd03a3e4c9a9 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/tomoyo/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/security/tomoyo/common.c +++ b/security/tomoyo/common.c @@ -2657,13 +2657,14 @@ ssize_t tomoyo_write_control(struct tomo { 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. */