On Fri, Jul 22, 2016 at 8:08 PM, Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote:
> The code in imx_ldb_encoder_mode_set crashes with a NULL pointer
> dereference trying to access crtc->state->state, which was previously
> cleared by drm_atomic_helper_swap_state:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000010
> pgd = ae08c000
> [00000010] *pgd=3e00e831, *pte=00000000, *ppte=00000000
> Internal error: Oops: 17 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 1 PID: 102 Comm: kmsfb-manage Not tainted 4.7.0-rc5+ #232
> Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> task: ae058c40 ti: ae04e000 task.ti: ae04e000
> PC is at imx_ldb_encoder_mode_set+0x138/0x2f8
> LR is at 0xae881818
> pc : [<8051a8c8>] lr : [<ae881818>] psr: 600f0013
> sp : ae04fc70 ip : ae04fbb0 fp : ae04fcbc
> r10: ae8ea018 r9 : 00000000 r8 : ae246418
> r7 : ae8ea010 r6 : ae8ea308 r5 : 00000000 r4 : 00000000
> r3 : 00000000 r2 : 00000000 r1 : 00000110 r0 : 00000000
> Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> Control: 10c5387d Table: 3e08c04a DAC: 00000051
> Process kmsfb-manage (pid: 102, stack limit = 0xae04e210)
> Stack: (0xae04fc70 to 0xae050000)
> fc60: 043ce660 00000001 0000009e 043ce660
> fc80: 00000002 00000000 00000000 af75cf50 00001009 ae23f440 00000001 ae246418
> fca0: 8155a210 ae8ea308 8093c364 ae2464e0 ae04fcec ae04fcc0 804ef350 8051a79c
> fcc0: 00000004 00000004 ae23f440 af3f9000 ae881818 8155a210 af1af200 ae8ea020
> fce0: ae04fd1c ae04fcf0 80519124 804ef060 ae04fd34 00000000 00000000 00000000
> fd00: ae881818 ae23f440 80d4ec8c 00000000 ae04fd34 ae04fd20 804f00b4 80518fac
> fd20: ae23f440 00000000 ae04fd54 ae04fd38 804f2190 804f0074 ae23f440 af3f9000
> fd40: ae04fdd4 ae881818 ae04fd6c ae04fd58 80516390 804f20f4 ae23f440 00000000
> fd60: ae04fd8c ae04fd70 804f26f4 80516348 ae23a000 ae881818 00000001 af3f9000
> fd80: ae04fdac ae04fd90 80502c58 804f2678 ae04fe50 ae23f400 00000001 af3f9000
> fda0: ae04fe1c ae04fdb0 80507a1c 80502bf8 ae23a000 ae058c40 af1af200 ae23f400
> fdc0: ae23a000 af3f9000 ae881818 ae23a00c 80176c7c ae23a000 ae881818 af1af200
> fde0: 00000000 00000000 ae23f400 00000001 ae04fe1c 00000051 ae04fe50 8155a210
> fe00: 80932060 c06864a2 af3f9000 ae246200 ae04fefc ae04fe20 804f9718 805074e8
> fe20: ae04feac ae04fe30 80177360 8017631c 805074dc 00000068 00000068 00000062
> fe40: 00000068 000000a2 ae04fe50 7ef29688 7ef29c40 00000000 00000001 00000018
> fe60: 00000026 00000000 00000000 00000000 00000001 000115bc 05010500 05a0059f
> fe80: 03200000 03360321 00000337 0000003c 00000000 00000040 30383231 30303878
> fea0: 00000000 00000000 00000000 00000000 00000000 00000000 00004000 aea6a140
> fec0: 00000000 80d77b71 00000000 80283110 600f0013 7ef29688 af342bb0 ae250b40
> fee0: 80275440 00000003 ae04e000 00000000 ae04ff7c ae04ff00 80274ac8 804f957c
> ff00: 80283128 80179030 00000000 00000000 80282fd8 ae1e0000 0000003d aea6a1d0
> ff20: 00000002 00000003 00004000 007f8c60 c06864a2 7ef29688 ae04e000 00000000
> ff40: ae04ff6c ae04ff50 80283260 80282fe4 00017050 ae250b41 00000003 ae250b40
> ff60: c06864a2 7ef29688 ae04e000 00000000 ae04ffa4 ae04ff80 80275440 80274a20
> ff80: 00017050 00000001 007f8c60 00000036 801088a4 ae04e000 00000000 ae04ffa8
> ffa0: 80108700 80275408 00017050 00000001 00000003 c06864a2 7ef29688 000115bc
> ffc0: 00017050 00000001 007f8c60 00000036 00000003 00000000 00000026 00000018
> ffe0: 00016f28 7ef29684 0000b7d9 76e4a1e6 400f0030 00000003 3ff7e861 3ff7ec61
> Backtrace:
> [<8051a790>] (imx_ldb_encoder_mode_set) from [<804ef350>] (drm_atomic_helper_commit_modeset_disables+0x2fc/0x3f0)
> r10:ae2464e0 r9:8093c364 r8:ae8ea308 r7:8155a210 r6:ae246418 r5:00000001
> r4:ae23f440
> [<804ef054>] (drm_atomic_helper_commit_modeset_disables) from [<80519124>] (imx_drm_atomic_commit_tail+0x184/0x1e0)
> r10:ae8ea020 r9:af1af200 r8:8155a210 r7:ae881818 r6:af3f9000 r5:ae23f440
> r4:00000004 r3:00000004
> [<80518fa0>] (imx_drm_atomic_commit_tail) from [<804f00b4>] (commit_tail+0x4c/0x68)
> r6:00000000 r5:80d4ec8c r4:ae23f440
> [<804f0068>] (commit_tail) from [<804f2190>] (drm_atomic_helper_commit+0xa8/0xd4)
> r5:00000000 r4:ae23f440
> [<804f20e8>] (drm_atomic_helper_commit) from [<80516390>] (drm_atomic_commit+0x54/0x74)
> r7:ae881818 r6:ae04fdd4 r5:af3f9000 r4:ae23f440
> [<8051633c>] (drm_atomic_commit) from [<804f26f4>] (drm_atomic_helper_set_config+0x88/0xac)
> r5:00000000 r4:ae23f440
> [<804f266c>] (drm_atomic_helper_set_config) from [<80502c58>] (drm_mode_set_config_internal+0x6c/0xf4)
> r7:af3f9000 r6:00000001 r5:ae881818 r4:ae23a000
> [<80502bec>] (drm_mode_set_config_internal) from [<80507a1c>] (drm_mode_setcrtc+0x540/0x5b8)
> r7:af3f9000 r6:00000001 r5:ae23f400 r4:ae04fe50
> [<805074dc>] (drm_mode_setcrtc) from [<804f9718>] (drm_ioctl+0x1a8/0x46c)
> r10:ae246200 r9:af3f9000 r8:c06864a2 r7:80932060 r6:8155a210 r5:ae04fe50
> r4:00000051
> [<804f9570>] (drm_ioctl) from [<80274ac8>] (do_vfs_ioctl+0xb4/0x9e8)
> r10:00000000 r9:ae04e000 r8:00000003 r7:80275440 r6:ae250b40 r5:af342bb0
> r4:7ef29688
> [<80274a14>] (do_vfs_ioctl) from [<80275440>] (SyS_ioctl+0x44/0x6c)
> r10:00000000 r9:ae04e000 r8:7ef29688 r7:c06864a2 r6:ae250b40 r5:00000003
> r4:ae250b41
> [<802753fc>] (SyS_ioctl) from [<80108700>] (ret_fast_syscall+0x0/0x1c)
> r9:ae04e000 r8:801088a4 r7:00000036 r6:007f8c60 r5:00000001 r4:00017050
> Code: 1a000018 e596e034 e59e3368 e59331bc (e5930010)
> ---[ end trace 464e7d3c7f4b9706 ]---
>
> Instead of trying to walk only the connectors in atomic state to which we
> don't have access, just walk all connectors to find one connected to the
> current encoder and containing a bus_format description.
>
> Fixes: 49f98bc4d44a4 ("drm/imx: store internal bus configuration in crtc state")
> Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
Acked-by: Liu Ying <gnuiyl@xxxxxxxxx>
Regards,
Liu Ying
> ---
> Changes since v1:
> - Remove unused local variable crtc_state.
> - Find the connector by its connector->encoder field
> instead of comparing connector and encoder crtcs.
> ---
> drivers/gpu/drm/imx/imx-ldb.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
> index dc2b420..3ed2d50 100644
> --- a/drivers/gpu/drm/imx/imx-ldb.c
> +++ b/drivers/gpu/drm/imx/imx-ldb.c
> @@ -298,15 +298,12 @@ static void imx_ldb_encoder_mode_set(struct drm_encoder *encoder,
> }
>
> if (!bus_format) {
> - struct drm_connector_state *conn_state;
> struct drm_connector *connector;
> - int i;
>
> - for_each_connector_in_state(encoder->crtc->state->state,
> - connector, conn_state, i) {
> + drm_for_each_connector(connector, encoder->dev) {
> struct drm_display_info *di = &connector->display_info;
>
> - if (conn_state->crtc == encoder->crtc &&
> + if (connector->encoder == encoder &&
> di->num_bus_formats) {
> bus_format = di->bus_formats[0];
> break;
> --
> 2.8.1
>
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