[PATCH V3] mtd: rawnand: qcom: fix memory corruption that causes panic

[Md Sadre Alam]

On 4/18/2022 11:00 AM, Manivannan Sadhasivam wrote:
> On Mon, Apr 18, 2022 at 10:49:01AM +0530, Md Sadre Alam wrote:
>> This patch fixes a memory corruption that occurred in the
>> nand_scan() path for Hynix nand device.
>>
>> On boot, for Hynix nand device will panic at a weird place:
>> | Unable to handle kernel NULL pointer dereference at virtual
>>    address 00000070
>> | [00000070] *pgd=00000000
>> | Internal error: Oops: 5 [#1] PREEMPT SMP ARM
>> | Modules linked in:
>> | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-01473-g13ae1769cfb0
>>    #38
>> | Hardware name: Generic DT based system
>> | PC is at nandc_set_reg+0x8/0x1c
>> | LR is at qcom_nandc_command+0x20c/0x5d0
>> | pc : [<c088b74c>]    lr : [<c088d9c8>]    psr: 00000113
>> | sp : c14adc50  ip : c14ee208  fp : c0cc970c
>> | r10: 000000a3  r9 : 00000000  r8 : 00000040
>> | r7 : c16f6a00  r6 : 00000090  r5 : 00000004  r4 :c14ee040
>> | r3 : 00000000  r2 : 0000000b  r1 : 00000000  r0 :c14ee040
>> | Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM Segment none
>> | Control: 10c5387d  Table: 8020406a  DAC: 00000051
>> | Register r0 information: slab kmalloc-2k start c14ee000 pointer offset
>>    64 size 2048
>> | Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
>> | nandc_set_reg from qcom_nandc_command+0x20c/0x5d0
>> | qcom_nandc_command from nand_readid_op+0x198/0x1e8
>> | nand_readid_op from hynix_nand_has_valid_jedecid+0x30/0x78
>> | hynix_nand_has_valid_jedecid from hynix_nand_init+0xb8/0x454
>> | hynix_nand_init from nand_scan_with_ids+0xa30/0x14a8
>> | nand_scan_with_ids from qcom_nandc_probe+0x648/0x7b0
>> | qcom_nandc_probe from platform_probe+0x58/0xac
>>
>> 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_command() to memset much more than what was initially
>> allocated by alloc_bam_transaction().
>>
>> This patch will update nandc->max_cwperpage 1 to 4 after nand_scan()
>> returns, and remove updating nandc->max_cwperpage from
>> qcom_nand_attach_chip call back.
> The above statement is still wrong.
    Updated in V4 patch.
>
>> Cc: stable at vger.kernel.org
>> Fixes: 6a3cec64f18c ("mtd: rawnand: qcom: convert driver to nand_scan()")
>> Reported-by: Konrad Dybcio <konrad.dybcio at somainline.org>
>> Signed-off-by: Md Sadre Alam <quic_mdalam at quicinc.com>
>> Signed-off-by: Sricharan R <quic_srichara at quicinc.com>
>> ---
>> [V3]
>>   * Updated commit message Fixes, Cc, Reported-by
> Missing the previous changelogs.


   Updated in V4 patch.

>
> Thanks,
> Mani
>
>>   drivers/mtd/nand/raw/qcom_nandc.c | 24 +++++++++++++-----------
>>   1 file changed, 13 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
>> index 1a77542..048b255 100644
>> --- a/drivers/mtd/nand/raw/qcom_nandc.c
>> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
>> @@ -2651,10 +2651,23 @@ static int qcom_nand_attach_chip(struct nand_chip *chip)
>>   	ecc->engine_type = NAND_ECC_ENGINE_TYPE_ON_HOST;
>>   
>>   	mtd_set_ooblayout(mtd, &qcom_nand_ooblayout_ops);
>> +	/* Free the initially allocated BAM transaction for reading the ONFI params */
>> +	if (nandc->props->is_bam)
>> +		free_bam_transaction(nandc);
>>   
>>   	nandc->max_cwperpage = max_t(unsigned int, nandc->max_cwperpage,
>>   				     cwperpage);
>>   
>> +	/* Now allocate the BAM transaction based on updated max_cwperpage */
>> +	if (nandc->props->is_bam) {
>> +		nandc->bam_txn = alloc_bam_transaction(nandc);
>> +		if (!nandc->bam_txn) {
>> +			dev_err(nandc->dev,
>> +				"failed to allocate bam transaction\n");
>> +			return -ENOMEM;
>> +		}
>> +	}
>> +
>>   	/*
>>   	 * DATA_UD_BYTES varies based on whether the read/write command protects
>>   	 * spare data with ECC too. We protect spare data by default, so we set
>> @@ -2955,17 +2968,6 @@ 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");
>> -			nand_cleanup(chip);
>> -			return -ENOMEM;
>> -		}
>> -	}
>> -
>>   	ret = mtd_device_parse_register(mtd, probes, NULL, NULL, 0);
>>   	if (ret)
>>   		nand_cleanup(chip);
>> -- 
>> 2.7.4
>>