From c942c462411e4757aafba73bf13b5e5c7a4b62ca Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Sun, 23 Dec 2018 00:38:55 +0100 Subject: [PATCH] mtd: rawnand: qcom: fix memory corruption that causes panic This patch fixes a memory corruption that occured 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 00000000 | 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+0x7a0/0x7dc) | [] (allocate_partition) from [] (add_mtd_partitions+0x58/0x10c) | [] (add_mtd_partitions) from [] (parse_mtd_partitions+0x310/0x338) | [] (parse_mtd_partitions) from [] (mtd_device_parse_register+0x60/0x15c) | [] (mtd_device_parse_register) from [] (qcom_nandc_probe+0x770/0x8f4) | [] (qcom_nandc_probe) from [] (platform_drv_probe+0x34/0x70) 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(). Hence, this patch restores the old behavior by performing the alloc_bam_transaction() after the chip was identified. 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(-) --- a/drivers/mtd/nand/raw/qcom_nandc.c +++ b/drivers/mtd/nand/raw/qcom_nandc.c @@ -2839,6 +2839,16 @@ static int qcom_nand_host_init_and_regis 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); @@ -2853,16 +2863,6 @@ static int qcom_probe_nand_devices(struc 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) {