In older versions of the IIO framework it was possible to pass a completely different set of channels to iio_buffer_register() as the one that is assigned to the IIO device. Commit 959d2952d124 ("staging:iio: make iio_sw_buffer_preenable much more general.") introduced a restriction that requires that the set of channels that is passed to iio_buffer_register() is a subset of the channels assigned to the IIO device as the IIO core will use the list of channels that is assigned to the device to lookup a channel by scan index in iio_compute_scan_bytes(). If it can not find the channel the function will crash. This patch fixes the issue by making sure that the same set of channels is assigned to the IIO device and passed to iio_buffer_register(). Fixes the follow NULL pointer derefernce kernel crash: Unable to handle kernel NULL pointer dereference at virtual address 00000016 pgd = d53d0000 [00000016] *pgd=1534e831, *pte=00000000, *ppte=00000000 Internal error: Oops: 17 [#1] PREEMPT SMP ARM Modules linked in: CPU: 1 PID: 1626 Comm: bash Not tainted 3.15.0-19969-g2a180eb-dirty #9545 task: d6c124c0 ti: d539a000 task.ti: d539a000 PC is at iio_compute_scan_bytes+0x34/0xa8 LR is at iio_compute_scan_bytes+0x34/0xa8 pc : [<c03052e4>] lr : [<c03052e4>] psr: 60070013 sp : d539beb8 ip : 00000001 fp : 00000000 r10: 00000002 r9 : 00000000 r8 : 00000001 r7 : 00000000 r6 : d6dc8800 r5 : d7571000 r4 : 00000002 r3 : d7571000 r2 : 00000044 r1 : 00000001 r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user Control: 18c5387d Table: 153d004a DAC: 00000015 Process bash (pid: 1626, stack limit = 0xd539a240) Stack: (0xd539beb8 to 0xd539c000) bea0: c02fc0e4 d7571000 bec0: d76c1640 d6dc8800 d757117c 00000000 d757112c c0305b04 d76c1690 d76c1640 bee0: d7571188 00000002 00000000 d7571000 d539a000 00000000 000dd1c8 c0305d54 bf00: d7571010 0160b868 00000002 c69d3900 d7573278 d7573308 c69d3900 c01ece90 bf20: 00000002 c0103fac c0103f6c d539bf88 00000002 c69d3b00 c69d3b0c c0103468 bf40: 00000000 00000000 d7694a00 00000002 000af408 d539bf88 c000dd84 c00b2f94 bf60: d7694a00 000af408 00000002 d7694a00 d7694a00 00000002 000af408 c000dd84 bf80: 00000000 c00b32d0 00000000 00000000 00000002 b6f1aa78 00000002 000af408 bfa0: 00000004 c000dc00 b6f1aa78 00000002 00000001 000af408 00000002 00000000 bfc0: b6f1aa78 00000002 000af408 00000004 be806a4c 000a6094 00000000 000dd1c8 bfe0: 00000000 be8069cc b6e8ab77 b6ec125c 40070010 00000001 22940489 154a5007 [<c03052e4>] (iio_compute_scan_bytes) from [<c0305b04>] (__iio_update_buffers+0x248/0x438) [<c0305b04>] (__iio_update_buffers) from [<c0305d54>] (iio_buffer_store_enable+0x60/0x7c) [<c0305d54>] (iio_buffer_store_enable) from [<c01ece90>] (dev_attr_store+0x18/0x24) [<c01ece90>] (dev_attr_store) from [<c0103fac>] (sysfs_kf_write+0x40/0x4c) [<c0103fac>] (sysfs_kf_write) from [<c0103468>] (kernfs_fop_write+0x110/0x154) [<c0103468>] (kernfs_fop_write) from [<c00b2f94>] (vfs_write+0xd0/0x160) [<c00b2f94>] (vfs_write) from [<c00b32d0>] (SyS_write+0x40/0x78) [<c00b32d0>] (SyS_write) from [<c000dc00>] (ret_fast_syscall+0x0/0x30) Code: ea00000e e1a01008 e1a00005 ebfff6fc (e5d0a016) Fixes: 959d2952d124 ("staging:iio: make iio_sw_buffer_preenable much more general.") Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx> --- No changes since v1 --- drivers/staging/iio/impedance-analyzer/ad5933.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c index d0c89d0..9a6665d 100644 --- a/drivers/staging/iio/impedance-analyzer/ad5933.c +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c @@ -115,6 +115,7 @@ static const struct iio_chan_spec ad5933_channels[] = { .channel = 0, .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), .address = AD5933_REG_TEMP_DATA, + .scan_index = -1, .scan_type = { .sign = 's', .realbits = 14, @@ -125,8 +126,6 @@ static const struct iio_chan_spec ad5933_channels[] = { .indexed = 1, .channel = 0, .extend_name = "real_raw", - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | - BIT(IIO_CHAN_INFO_SCALE), .address = AD5933_REG_REAL_DATA, .scan_index = 0, .scan_type = { @@ -139,8 +138,6 @@ static const struct iio_chan_spec ad5933_channels[] = { .indexed = 1, .channel = 0, .extend_name = "imag_raw", - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | - BIT(IIO_CHAN_INFO_SCALE), .address = AD5933_REG_IMAG_DATA, .scan_index = 1, .scan_type = { @@ -749,14 +746,14 @@ static int ad5933_probe(struct i2c_client *client, indio_dev->name = id->name; indio_dev->modes = INDIO_DIRECT_MODE; indio_dev->channels = ad5933_channels; - indio_dev->num_channels = 1; /* only register temp0_input */ + indio_dev->num_channels = ARRAY_SIZE(ad5933_channels); ret = ad5933_register_ring_funcs_and_init(indio_dev); if (ret) goto error_disable_reg; - /* skip temp0_input, register in0_(real|imag)_raw */ - ret = iio_buffer_register(indio_dev, &ad5933_channels[1], 2); + ret = iio_buffer_register(indio_dev, ad5933_channels, + ARRAY_SIZE(ad5933_channels)); if (ret) goto error_unreg_ring; -- 1.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html