概要

There are null-ptr-deref vulnerabilities in drivers/net/slip of linux that allow attacker tocrash linux kernel by simulating slip network card from user-space of linux.[Root cause]When a slip driver is detaching, the slip_close() will act tocleanup necessary resources and sl->tty is set to NULL inslip_close(). Meanwhile, the packet we transmit is blocked,sl_tx_timeout() will be called. Although slip_close() andsl_tx_timeout() use sl->lock to synchronize, we don`t judgewhether sl-> tty equals to NULL in sl_tx_timeout() and thenull pointer dereference bug will happen.(Thread 1) | (Thread 2)| slip_close()| spin_lock_bh(& sl-> lock) sl-> tty = NULL //(1)sl_tx_timeout() | spin_unlock_bh(& sl->lock)spin_lock(& sl-> lock);tty_chars_in_buffer(sl-> tty)|if (tty-> ops-> ..) //(2)synchronize_rcu()We set NULL to sl-> tty in position (1) and dereference sl-> ttyin position (2).

CVSS v3 指标

安全公告

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