[PATCH 4.12 076/106] packet: fix use-after-free in prb_retire_rx_blk_timer_expired()

4.12-stable review patch. If anyone has any objections, please let me know. -- From: WANG Cong [ Upstream commit c800aaf8d869f2b9b47b10c5c312fe19f0a94042 ] There are multiple reports showing we have a use-after-free in the timer

[PATCH 4.12 076/106] packet: fix use-after-free in prb_retire_rx_blk_timer_expired()

4.12-stable review patch. If anyone has any objections, please let me know. -- From: WANG Cong [ Upstream commit c800aaf8d869f2b9b47b10c5c312fe19f0a94042 ] There are multiple reports showing we have a use-after-free in the timer prb_retire_rx_blk_timer_expired(), where we