From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-x342.google.com ([2a00:1450:4864:20::342]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gargD-00023p-NC for linux-mtd@lists.infradead.org; Sun, 23 Dec 2018 00:31:43 +0000 Received: by mail-wm1-x342.google.com with SMTP id y139so8467973wmc.5 for ; Sat, 22 Dec 2018 16:31:30 -0800 (PST) From: Christian Lamparter To: linux-mtd@lists.infradead.org Cc: Abhishek Sahu , Marek Vasut , Brian Norris , David Woodhouse , Richard Weinberger , Miquel Raynal , Boris Brezillon Subject: [PATCH] mtd: rawnand: qcom: fix memory corruption that causes panic Date: Sun, 23 Dec 2018 01:31:26 +0100 Message-Id: <20181223003126.1704-1-chunkeey@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This patch fixes a memory corruption that occurred in the qcom-nandc driver since it was converted to nand_scan(). On boot, an affected device will panic from a NPE at a weird place: | Unable to handle kernel NULL pointer dereference at virtual address 0 | pgd = (ptrval) | [00000000] *pgd=00000000 | Internal error: Oops: 80000005 [#1] SMP ARM | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.9 #0 | Hardware name: Generic DT based system | PC is at (null) | LR is at nand_block_isbad+0x90/0xa4 | pc : [<00000000>] lr : [] psr: 80000013 | sp : cf839d40 ip : 00000000 fp : cfae9e20 | r10: cf815810 r9 : 00000000 r8 : 00000000 | r7 : 00000000 r6 : 00000000 r5 : 00000001 r4 : cf815810 | r3 : 00000000 r2 : cfae9810 r1 : ffffffff r0 : cf815810 | Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none | Control: 10c5387d Table: 8020406a DAC: 00000051 | Process swapper/0 (pid: 1, stack limit = 0x(ptrval)) | [] (nand_block_isbad) from [] | [] (allocate_partition) from [] | [] (add_mtd_partitions) from [] | [] (parse_mtd_partitions) from [] | [] (mtd_device_parse_register) from [] | [] (qcom_nandc_probe) from [] The problem is that the nand_scan()'s qcom_nand_attach_chip callback is updating the nandc->max_cwperpage from 1 to 4. This causes the sg_init_table of clear_bam_transaction() in the driver's qcom_nandc_block_bad() to memset much more than what was initially allocated by alloc_bam_transaction(). This patch restores the old behavior by reallocating the shared bam transaction alloc_bam_transaction() after the chip was identified, but before mtd_device_parse_register() (which is an alias for mtd_device_register() - see panic) gets called. This fixes the corruption and the driver is working again. Cc: stable@vger.kernel.org Fixes: 6a3cec64f18c ("mtd: rawnand: qcom: convert driver to nand_scan()") Signed-off-by: Christian Lamparter --- drivers/mtd/nand/raw/qcom_nandc.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c index 699d3cf49c6d..7c42a57aca1f 100644 --- a/drivers/mtd/nand/raw/qcom_nandc.c +++ b/drivers/mtd/nand/raw/qcom_nandc.c @@ -2833,6 +2833,16 @@ static int qcom_nand_host_init_and_register(struct qcom_nand_controller *nandc, if (ret) return ret; + if (nandc->props->is_bam) { + free_bam_transaction(nandc); + nandc->bam_txn = alloc_bam_transaction(nandc); + if (!nandc->bam_txn) { + dev_err(nandc->dev, + "failed to allocate bam transaction\n"); + return -ENOMEM; + } + } + ret = mtd_device_register(mtd, NULL, 0); if (ret) nand_cleanup(chip); @@ -2847,16 +2857,6 @@ static int qcom_probe_nand_devices(struct qcom_nand_controller *nandc) struct qcom_nand_host *host; int ret; - if (nandc->props->is_bam) { - free_bam_transaction(nandc); - nandc->bam_txn = alloc_bam_transaction(nandc); - if (!nandc->bam_txn) { - dev_err(nandc->dev, - "failed to allocate bam transaction\n"); - return -ENOMEM; - } - } - for_each_available_child_of_node(dn, child) { host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL); if (!host) { -- 2.20.1