[PATCH V5] mtd: rawnand: qcom: fix memory corruption that causes panic

[Miquel Raynal]

On Mon, 2022-04-18 at 07:48:27 UTC, 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 or 8 based on page size.
> 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 or 8 based on page
> size in qcom_nand_attach_chip call back after freeing the previously
> allocated memory for bam txn as per nandc->max_cwperpage = 1 and then
> again allocating bam txn as per nandc->max_cwperpage = 4 or 8 based on
> page size in qcom_nand_attach_chip call back itself.
> 
> 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>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
> Co-developed-by: Sricharan R <quic_srichara at quicinc.com>
> Signed-off-by: Sricharan R <quic_srichara at quicinc.com>
> Signed-off-by: Md Sadre Alam <quic_mdalam at quicinc.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.

Miquel