On Mon, Nov 11, 2013 at 8:40 AM, Huang Shijie <b32955@xxxxxxxxxxxxx> wrote: > The imx23 board will check the fingerprint, so it will call the > mx23_check_transcription_stamp. This function will use @chip->buffers->databuf > as its buffer which is allocated in the nand_scan_tail(). > > Unfortunately, the mx23_check_transcription_stamp is called before the > nand_scan_tail(). So we will meet a NULL pointer bug: > > -------------------------------------------------------------------- > [ 1.150000] NAND device: Manufacturer ID: 0xec, Chip ID: 0xd7 (Samsung NAND 4GiB 3,3V 8-bit), 4096MiB, page size: 4096, OOB size: 8 > [ 1.160000] Unable to handle kernel NULL pointer dereference at virtual address 000005d0 > [ 1.170000] pgd = c0004000 > [ 1.170000] [000005d0] *pgd=00000000 > [ 1.180000] Internal error: Oops: 5 [#1] ARM > [ 1.180000] Modules linked in: > [ 1.180000] CPU: 0 PID: 1 Comm: swapper Not tainted 3.12.0 #89 > [ 1.180000] task: c7440000 ti: c743a000 task.ti: c743a000 > [ 1.180000] PC is at memcmp+0x10/0x54 > [ 1.180000] LR is at gpmi_nand_probe+0x42c/0x894 > [ 1.180000] pc : [<c025fcb0>] lr : [<c02f6a68>] psr: 20000053 > [ 1.180000] sp : c743be2c ip : 600000d3 fp : ffffffff > [ 1.180000] r10: 000005d0 r9 : c02f5f08 r8 : 00000000 > [ 1.180000] r7 : c75858a8 r6 : c75858a8 r5 : c7585b18 r4 : c7585800 > [ 1.180000] r3 : 000005d0 r2 : 00000004 r1 : c05c33e4 r0 : 000005d0 > [ 1.180000] Flags: nzCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment kernel > [ 1.180000] Control: 0005317f Table: 40004000 DAC: 00000017 > [ 1.180000] Process swapper (pid: 1, stack limit = 0xc743a1c0) > -------------------------------------------------------------------- > > This patch does two things: > 1.) Allocates the @chip->buffers itself, and set the NAND_OWN_BUFFERS > for chip->options. > 2.) Also initialize the @chip->oob_poi which is used by the > mx23_write_transcription_stamp(). We replace the @chip->ecc.write_page_raw > with chip->write_buf, since the the @chip->ecc.write_page_raw is > initialize in the nand_scan_tail() too. If we not do so, we will meet > a NULL pointer too. > > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Fabio Estevam <festevam@xxxxxxxxx> > Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx> > --- > v1 --> v2: do not use a local array any more. > --- > drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 8 +++++++- > 1 files changed, 7 insertions(+), 1 deletions(-) > > diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c > index 6e74917..a2531e7 100644 > --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c > +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c > @@ -1465,7 +1465,7 @@ static int mx23_write_transcription_stamp(struct gpmi_nand_data *this) > /* Write the first page of the current stride. */ > dev_dbg(dev, "Writing an NCB fingerprint in page 0x%x\n", page); > chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page); > - chip->ecc.write_page_raw(mtd, chip, buffer, 0); > + chip->write_buf(mtd, buffer, mtd->writesize); > chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1); > > /* Wait for the write to finish. */ > @@ -1609,6 +1609,12 @@ static int gpmi_init_last(struct gpmi_nand_data *this) > struct bch_geometry *bch_geo = &this->bch_geometry; > int ret; > > + chip->buffers = kzalloc(sizeof(*chip->buffers), GFP_KERNEL); > + if (!chip->buffers) > + return -ENOMEM; > + chip->options |= NAND_OWN_BUFFERS; > + chip->oob_poi = chip->buffers->databuf + mtd->writesize; It seems that this patch is making more changes than the required to fix the NULL dereference bug. I think that a simpler fix would be just to allocate the buffer in mx23_check_transcription_stamp() with kzalloc. Will submit a proposal now. Regards, Fabio Estevam -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html