Userspace can disable links and create pipelines that
do not start with a source entity. Trying to stream
from such a pipeline should fail with -EPIPE
currently this is not handled and cause kernel crash.
Reproducing the crash:
media-ctl -d0 -l "5:1->21:0[0]" -v
v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video2
Panic message:
[ 39.078841][ T248] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 39.079338][ T248] #PF: supervisor read access in kernel mode
[ 39.079704][ T248] #PF: error_code(0x0000) - not-present page
[ 39.080071][ T248] PGD 0 P4D 0
[ 39.080279][ T248] Oops: 0000 [#1] SMP PTI
[ 39.080546][ T248] CPU: 0 PID: 248 Comm: vimc-streamer t Not tainted 5.4.0-rc1+ #17
[ 39.081030][ T248] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
[ 39.081779][ T248] RIP: 0010:vimc_sca_process_frame+0xdb/0x210 [vimc]
[ 39.082191][ T248] Code: 44 8d 0c 28 8b 93 a4 01 00 00 48 8b 8b 98 01 00 00 85 d2 74 40 48 8b 74 24 10 8d 7a ff 4c 01 c9 31 d2 4c 01 fe eb 03 4c 89 c2 <44> 0f b6 04 16 44 88 04 11 4c 8d 42 01 48 39 fa 75 eb 8b 93 a4 01
[ 39.083436][ T248] RSP: 0018:ffffb15a005abe90 EFLAGS: 00010246
[ 39.083808][ T248] RAX: 0000000000000000 RBX: ffffa3fdc46d2e00 RCX: ffffb15a02579000
[ 39.084298][ T248] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
[ 39.084792][ T248] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 39.085280][ T248] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[ 39.085770][ T248] R13: ffffa3fdc46d2ee0 R14: 0000000000000000 R15: 0000000000000000
[ 39.086258][ T248] FS: 0000000000000000(0000) GS:ffffa3fdc7800000(0000) knlGS:0000000000000000
[ 39.086806][ T248] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 39.087217][ T248] CR2: 0000000000000000 CR3: 0000000003c92005 CR4: 0000000000360ef0
[ 39.087706][ T248] Call Trace:
[ 39.087909][ T248] ? vimc_streamer_pipeline_terminate+0x90/0x90 [vimc]
[ 39.088318][ T248] vimc_streamer_thread+0x7c/0xe0 [vimc]
[ 39.088663][ T248] kthread+0x10d/0x130
[ 39.088919][ T248] ? kthread_park+0x80/0x80
[ 39.089205][ T248] ret_from_fork+0x35/0x40
[ 39.089475][ T248] Modules linked in: vimc videobuf2_vmalloc videobuf2_memops v4l2_tpg videobuf2_v4l2 videobuf2_common videodev mc
[ 39.090208][ T248] CR2: 0000000000000000
[ 39.090463][ T248] ---[ end trace 697650fefbf78bee ]---
[ 39.090796][ T248] RIP: 0010:vimc_sca_process_frame+0xdb/0x210 [vimc]
[ 39.091209][ T248] Code: 44 8d 0c 28 8b 93 a4 01 00 00 48 8b 8b 98 01 00 00 85 d2 74 40 48 8b 74 24 10 8d 7a ff 4c 01 c9 31 d2 4c 01 fe eb 03 4c 89 c2 <44> 0f b6 04 16 44 88 04 11 4c 8d 42 01 48 39 fa 75 eb 8b 93 a4 01
[ 39.092417][ T248] RSP: 0018:ffffb15a005abe90 EFLAGS: 00010246
[ 39.092789][ T248] RAX: 0000000000000000 RBX: ffffa3fdc46d2e00 RCX: ffffb15a02579000
[ 39.093278][ T248] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
[ 39.093766][ T248] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 39.094254][ T248] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[ 39.094742][ T248] R13: ffffa3fdc46d2ee0 R14: 0000000000000000 R15: 0000000000000000
[ 39.095309][ T248] FS: 0000000000000000(0000) GS:ffffa3fdc7800000(0000) knlGS:0000000000000000
[ 39.095974][ T248] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 39.096372][ T248] CR2: 0000000000000000 CR3: 0000000003c92005 CR4: 0000000000360ef0
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
---
Changes since v5:
1. change the documentation of vimc_is_source
2. rewrite the patch so that it has the minimal code that fixes the crash
drivers/media/platform/vimc/vimc-common.c | 10 ++++++++++
drivers/media/platform/vimc/vimc-common.h | 8 ++++++++
drivers/media/platform/vimc/vimc-streamer.c | 13 +++++++++++--
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/drivers/media/platform/vimc/vimc-common.c b/drivers/media/platform/vimc/vimc-common.c
index 2a0c40e9ae88..64aa71230522 100644
--- a/drivers/media/platform/vimc/vimc-common.c
+++ b/drivers/media/platform/vimc/vimc-common.c
@@ -164,6 +164,16 @@ static const struct vimc_pix_map vimc_pix_map_list[] = {
},
};
+bool vimc_is_source(struct media_entity *ent)
+{
+ unsigned int i;
+
+ for (i = 0; i < ent->num_pads; i++)
+ if (ent->pads[i].flags & MEDIA_PAD_FL_SINK)
+ return false;
+ return true;
+}
+
const struct vimc_pix_map *vimc_pix_map_by_index(unsigned int i)
{
if (i >= ARRAY_SIZE(vimc_pix_map_list))
diff --git a/drivers/media/platform/vimc/vimc-common.h b/drivers/media/platform/vimc/vimc-common.h
index c75401a36312..91375c5cdc2b 100644
--- a/drivers/media/platform/vimc/vimc-common.h
+++ b/drivers/media/platform/vimc/vimc-common.h
@@ -139,6 +139,14 @@ struct vimc_ent_config {
void (*rm)(struct vimc_device *vimc, struct vimc_ent_device *ved);
};
+/**
+ * vimc_is_source - returns true if the entity has only source pads
+ *
+ * @ent: pointer to &struct media_entity
+ *
+ */
+bool vimc_is_source(struct media_entity *ent);
+
/* prototypes for vimc_ent_config add and rm hooks */
struct vimc_ent_device *vimc_cap_add(struct vimc_device *vimc,
const char *vcfg_name);
diff --git a/drivers/media/platform/vimc/vimc-streamer.c b/drivers/media/platform/vimc/vimc-streamer.c
index 1349be188a5b..cd6b55433c9e 100644
--- a/drivers/media/platform/vimc/vimc-streamer.c
+++ b/drivers/media/platform/vimc/vimc-streamer.c
@@ -104,9 +104,18 @@ static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
}
entity = vimc_get_source_entity(ved->ent);
- /* Check if the end of the pipeline was reached*/
- if (!entity)
+ /* Check if the end of the pipeline was reached */
+ if (!entity) {
+ /* the first entity of the pipe should be source only */
+ if (!vimc_is_source(ved->ent)) {
+ dev_err(ved->dev,
+ "first entity in the pipe '%s' is not a source\n",
+ ved->ent->name);
+ vimc_streamer_pipeline_terminate(stream);
+ return -EPIPE;
+ }
return 0;
+ }
/* Get the next device in the pipeline */
if (is_media_entity_v4l2_subdev(entity)) {
--
2.20.1
