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([182.150.55.91]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c7f58cbe35sm14624385ad.0.2026.06.25.00.11.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Jun 2026 00:11:45 -0700 (PDT) From: Liem To: Oleksij Rempel Cc: Andi Shyti , Pengutronix Kernel Team , Frank Li , Sascha Hauer , Fabio Estevam , Biwen Li , Wolfram Sang , linux-i2c@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Liem Subject: [PATCH] i2c: imx: Fix slave registration error path and missing NULL check Date: Thu, 25 Jun 2026 15:11:30 +0800 Message-Id: <20260625071130.93544-1-liem16213@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit There are two issues that affect the i2c-imx slave handling: 1. In i2c_imx_reg_slave(), i2c_imx->slave is checked at the beginning and the function returns -EBUSY if it is non-NULL. If pm_runtime_resume_and_get() fails later, the error path returns without clearing i2c_imx->slave, leaving it non-NULL. Subsequent attempts to register a slave will then immediately fail with -EBUSY, making it impossible to register the slave again. Fix by setting i2c_imx->slave = NULL on the error path. 2. In i2c_imx_unreg_slave(), the slave pointer is set to NULL after disabling interrupts. However, a pending interrupt might already have started a timer (e.g. for slave event processing) before the pointer was cleared. The timer callback i2c_imx_slave_event() dereferences i2c_imx->slave without a NULL check, which results in a use-after-free / NULL pointer dereference. Prevent this by checking that i2c_imx->slave is valid before calling i2c_slave_event() and updating the last_slave_event field. Both issues can trigger a kernel oops or permanent slave registration failure under certain race conditions. Add the missing NULL assignment and the missing NULL check to harden the slave path. Fixes: f7414cd6923f ("i2c: imx: support slave mode for imx I2C driver") Cc: stable@vger.kernel.org Signed-off-by: Liem --- drivers/i2c/busses/i2c-imx.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 28313d0fad37..4f7bcbeecfd0 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -775,8 +775,10 @@ static void i2c_imx_enable_bus_idle(struct imx_i2c_struct *i2c_imx) static void i2c_imx_slave_event(struct imx_i2c_struct *i2c_imx, enum i2c_slave_event event, u8 *val) { - i2c_slave_event(i2c_imx->slave, event, val); - i2c_imx->last_slave_event = event; + if (i2c_imx->slave) { + i2c_slave_event(i2c_imx->slave, event, val); + i2c_imx->last_slave_event = event; + } } static void i2c_imx_slave_finish_op(struct imx_i2c_struct *i2c_imx) @@ -936,6 +938,7 @@ static int i2c_imx_reg_slave(struct i2c_client *client) /* Resume */ ret = pm_runtime_resume_and_get(i2c_imx->adapter.dev.parent); if (ret < 0) { + i2c_imx->slave = NULL; dev_err(&i2c_imx->adapter.dev, "failed to resume i2c controller"); return ret; } -- 2.34.1