The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From be94215be1ab19e5d38f50962f611c88d4bfc83a Mon Sep 17 00:00:00 2001
From: Xiang Chen chenxiang66@hisilicon.com Date: Thu, 1 Apr 2021 15:34:46 +0800 Subject: [PATCH] mtd: spi-nor: core: Fix an issue of releasing resources during read/write
If rmmod the driver during read or write, the driver will release the resources which are used during read or write, so it is possible to refer to NULL pointer.
Use the testcase "mtd_debug read /dev/mtd0 0xc00000 0x400000 dest_file & sleep 0.5;rmmod spi_hisi_sfc_v3xx.ko", the issue can be reproduced in hisi_sfc_v3xx driver.
To avoid the issue, fill the interface _get_device and _put_device of mtd_info to grab the reference to the spi controller driver module, so the request of rmmod the driver is rejected before read/write is finished.
Fixes: b199489d37b2 ("mtd: spi-nor: add the framework for SPI NOR") Signed-off-by: Xiang Chen chenxiang66@hisilicon.com Signed-off-by: Yicong Yang yangyicong@hisilicon.com Signed-off-by: Tudor Ambarus tudor.ambarus@microchip.com Tested-by: Michael Walle michael@walle.cc Tested-by: Tudor Ambarus tudor.ambarus@microchip.com Reviewed-by: Michael Walle michael@walle.cc Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/1617262486-4223-1-git-send-email-yangyicong@hisili...
diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c index 8cf3cf92129e..bd2c7717eb10 100644 --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -2905,6 +2905,37 @@ static void spi_nor_resume(struct mtd_info *mtd) dev_err(dev, "resume() failed\n"); }
+static int spi_nor_get_device(struct mtd_info *mtd) +{ + struct mtd_info *master = mtd_get_master(mtd); + struct spi_nor *nor = mtd_to_spi_nor(master); + struct device *dev; + + if (nor->spimem) + dev = nor->spimem->spi->controller->dev.parent; + else + dev = nor->dev; + + if (!try_module_get(dev->driver->owner)) + return -ENODEV; + + return 0; +} + +static void spi_nor_put_device(struct mtd_info *mtd) +{ + struct mtd_info *master = mtd_get_master(mtd); + struct spi_nor *nor = mtd_to_spi_nor(master); + struct device *dev; + + if (nor->spimem) + dev = nor->spimem->spi->controller->dev.parent; + else + dev = nor->dev; + + module_put(dev->driver->owner); +} + void spi_nor_restore(struct spi_nor *nor) { /* restore the addressing mode */ @@ -3099,6 +3130,8 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, mtd->_read = spi_nor_read; mtd->_suspend = spi_nor_suspend; mtd->_resume = spi_nor_resume; + mtd->_get_device = spi_nor_get_device; + mtd->_put_device = spi_nor_put_device;
if (info->flags & USE_FSR) nor->flags |= SNOR_F_USE_FSR;