CVE-2021-47355 Information

Description

In the Linux kernel the following vulnerability has been resolved:

atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

This module’s remove path calls del_timer(). However that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver’s remove function has finished which would result in a use-after-free.

Fix by calling del_timer_sync() which makes sure the timer handler has finished and unable to re-schedule itself.

Reference

https://git.kernel.org/stable/c/99779c9d9ffc7775da6f7fd8a7c93ac61657bed5 https://git.kernel.org/stable/c/4e2a0848ea2cab0716d46f85a8ccd5fa9a493e51 https://git.kernel.org/stable/c/c471569632654e57c83512e0fc1ba0dbb4544ad6 https://git.kernel.org/stable/c/a7a7b2848312cc4c3a42b6e42a8ab2e441857aba https://git.kernel.org/stable/c/bdf5334250c69fabf555b7322c75249ea7d5f148 https://git.kernel.org/stable/c/a7f7c42e31157d1f0871d6a8e1a0b73a6b4ea785 https://git.kernel.org/stable/c/2f958b6f6ba0854b39be748d21dfe71e0fe6580f https://git.kernel.org/stable/c/5b991df8881088448cb223e769e37cab8dd40706 https://git.kernel.org/stable/c/34e7434ba4e97f4b85c1423a59b2922ba7dff2ea