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[81.2.115.148]) by smtp.gmail.com with ESMTPSA id a186sm3577443wmh.33.2020.03.17.04.40.51 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2020 04:40:51 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PULL 09/11] m25p80: Improve command handling for unsupported commands Date: Tue, 17 Mar 2020 11:40:37 +0000 Message-Id: <20200317114039.26914-10-peter.maydell@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200317114039.26914-1-peter.maydell@linaro.org> References: <20200317114039.26914-1-peter.maydell@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:4864:20::342 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Guenter Roeck Whenever an unsupported command is encountered, the current code interprets each transferred byte as new command. Most of the time, those 'commands' are interpreted as new unknown commands. However, in rare cases, it may be that for example address or length information passed with the original command is by itself a valid command. If that happens, the state machine may get completely confused and, worst case, start writing data into the flash or even erase it. To avoid the problem, transition into STATE_READING_DATA and keep sending a value of 0 until the chip is deselected after encountering an unsupported command. Signed-off-by: Guenter Roeck Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Cédric Le Goater Signed-off-by: Peter Maydell --- hw/block/m25p80.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c index 53bf63856f5..82270884416 100644 --- a/hw/block/m25p80.c +++ b/hw/block/m25p80.c @@ -1161,6 +1161,11 @@ static void decode_new_cmd(Flash *s, uint32_t value) s->quad_enable = false; break; default: + s->pos = 0; + s->len = 1; + s->state = STATE_READING_DATA; + s->data_read_loop = true; + s->data[0] = 0; qemu_log_mask(LOG_GUEST_ERROR, "M25P80: Unknown cmd %x\n", value); break; }