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Tue, 20 Oct 2026 19:20:25 -0700 (PDT) Received: from osman.mioffice.cn ([43.224.245.178]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ad802917c3sm1979077a91.7.2026.10.20.19.20.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 19:20:24 -0700 (PDT) From: Zhan Xusheng To: Greg Kroah-Hartman , Jiri Slaby Cc: Mathieu Poirier , Dmitry Torokhov , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Zhan Xusheng , stable@vger.kernel.org Subject: [PATCH v3 2/2] tty: sysrq: reset the per-device key state when reparsing reset_seq Date: Wed, 21 Oct 2026 10:20:07 +0800 Message-ID: <20261021022007.1717207-3-zhanxusheng1024@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261021022007.1717207-1-zhanxusheng1024@gmail.com> References: <20261021022007.1717207-1-zhanxusheng1024@gmail.com> X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zhan Xusheng sysrq_parse_reset_sequence() clears reset_seq_cnt, but reset_keybit is only ever __set_bit() and reset_seq_len only ever incremented. struct sysrq_state is allocated once per input device in sysrq_connect() and lives until the device goes away, so both accumulate every time the sequence is reparsed, which happens whenever the mode 0644 reset_seq parameter is written. After writing 56,29,111 and then 59,60 a device keeps all five keys in reset_keybit with reset_seq_len 5, so the effective combination is the union of the old and the new sequence. Holding just 59 and 60 counts two of five and does nothing, while releasing a stale key drives reset_seq_cnt below zero. Clear both along with reset_seq_cnt. Also delete keyreset_timer: with sysrq_downtime_ms set, holding a full sequence arms it, and it is only deleted on a press outside the sequence or a release inside it. Dropping the old keys from reset_keybit removes both of those cancellations, so an already armed reset would survive into orderly_reboot(). Fixes: 154b7a489a5b ("Input: sysrq - allow specifying alternate reset sequence") Cc: stable@vger.kernel.org Signed-off-by: Zhan Xusheng --- drivers/tty/sysrq.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 4fd5b3ace9c40..bb202fc1ccf0b 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -691,6 +691,15 @@ static void sysrq_parse_reset_sequence(struct sysrq_state *state) int i; unsigned short key; + /* + * An armed reset belongs to the sequence being replaced: once the + * old keys are gone from reset_keybit their release no longer + * cancels it. + */ + timer_delete(&state->keyreset_timer); + + bitmap_zero(state->reset_keybit, KEY_CNT); + state->reset_seq_len = 0; state->reset_seq_cnt = 0; for (i = 0; i < len; i++) { -- 2.43.0