[PATCH 3.12 073/212] mtd: gpmi: fix the NULL pointer

From: Greg Kroah-Hartman
Date: Mon Dec 02 2013 - 15:07:33 EST


3.12-stable review patch. If anyone has any objections, please let me know.

------------------

From: Huang Shijie <b32955@xxxxxxxxxxxxx>

commit 885d71e5838f68d5dbee92ab952cc90ad6c1dc6b upstream.

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 rearrange the init procedure:
Set the NAND_SKIP_BBTSCAN to skip the nand scan firstly, and after we
set the proper settings, we will call the chip->scan_bbt() manually.

Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx>
Reported-by: Fabio Estevam <festevam@xxxxxxxxx>
Tested-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -1568,8 +1568,6 @@ static int gpmi_set_geometry(struct gpmi

static int gpmi_pre_bbt_scan(struct gpmi_nand_data *this)
{
- int ret;
-
/* Set up swap_block_mark, must be set before the gpmi_set_geometry() */
if (GPMI_IS_MX23(this))
this->swap_block_mark = false;
@@ -1577,12 +1575,8 @@ static int gpmi_pre_bbt_scan(struct gpmi
this->swap_block_mark = true;

/* Set up the medium geometry */
- ret = gpmi_set_geometry(this);
- if (ret)
- return ret;
+ return gpmi_set_geometry(this);

- /* NAND boot init, depends on the gpmi_set_geometry(). */
- return nand_boot_init(this);
}

static void gpmi_nfc_exit(struct gpmi_nand_data *this)
@@ -1672,10 +1666,16 @@ static int gpmi_nfc_init(struct gpmi_nan
if (ret)
goto err_out;

+ chip->options |= NAND_SKIP_BBTSCAN;
ret = nand_scan_tail(mtd);
if (ret)
goto err_out;

+ ret = nand_boot_init(this);
+ if (ret)
+ goto err_out;
+ chip->scan_bbt(mtd);
+
ppdata.of_node = this->pdev->dev.of_node;
ret = mtd_device_parse_register(mtd, NULL, &ppdata, NULL, 0);
if (ret)


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