Re: [PATCH] drm/v3d: Free the job and assign it to NULL if initialization fails

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On 1/11/24 04:13, Iago Toral wrote:
Ok, thanks for checking, you can add my R-B on the original patch then.


Applied to drm-misc/drm-misc-next-fixes!

Best Regards,
- Maíra

Iago

El mié, 10-01-2024 a las 07:42 -0300, Maira Canal escribió:
Hi Iago,

On 1/10/24 03:48, Iago Toral wrote:
I think this is fine, but I was wondering if it would be simpler
and
easier to just remove the sched cleanup from v3d_job_init and
instead
always rely on callers to eventually call v3d_job_cleanup for fail
paths, where we are already calling v3d_job_cleanup.

If we just remove `drm_sched_job_cleanup()` from `v3d_job_init()` we
trigger a use-after-free warning by the job refcount:

[   34.367222] ------------[ cut here ]------------
[   34.367235] refcount_t: underflow; use-after-free.
[   34.367274] WARNING: CPU: 0 PID: 1922 at lib/refcount.c:28
refcount_warn_saturate+0x108/0x148
[   34.367298] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer
snd_seq snd_seq_device algif_hash aes_neon_bs aes_neon_blk
algif_skcipher af_alg bnep hid_logitech_hidpp brcmfmac_wcc brcmfmac
hci_uart btbcm bluetooth vc4 brcmutil cfg80211 bcm2835_v4l2(C)
bcm2835_mmal_vchiq(C) binfmt_misc snd_soc_hdmi_codec videobuf2_v4l2
cec
ecdh_generic drm_display_helper videobuf2_vmalloc ecc
videobuf2_memops
drm_dma_helper videobuf2_common drm_kms_helper dwc2 raspberrypi_hwmon
videodev snd_soc_core i2c_brcmstb rfkill libaes hid_logitech_dj mc
v3d
snd_bcm2835(C) i2c_bcm2835 pwm_bcm2835 snd_pcm_dmaengine snd_pcm
gpu_sched snd_timer drm_shmem_helper snd nvmem_rmem uio_pdrv_genirq
uio
i2c_dev drm dm_mod fuse drm_panel_orientation_quirks backlight
configfs
ip_tables x_tables ipv6
[   34.367434] CPU: 0 PID: 1922 Comm: v3d_submit_cl Tainted:
G         C
          6.7.0-rc3-g632ca3c92f38-dirty #74
[   34.367441] Hardware name: Raspberry Pi 4 Model B Rev 1.5 (DT)
[   34.367444] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS
BTYPE=--)
[   34.367450] pc : refcount_warn_saturate+0x108/0x148
[   34.367456] lr : refcount_warn_saturate+0x108/0x148
[   34.367462] sp : ffffffc08341bb90
[   34.367465] x29: ffffffc08341bb90 x28: ffffff8102962400 x27:
ffffffee5592de88
[   34.367473] x26: ffffff8116503e00 x25: ffffff81213e8800 x24:
0000000000000048
[   34.367481] x23: ffffff8101088000 x22: ffffffc08341bcf0 x21:
00000000ffffffea
[   34.367489] x20: ffffff8102962400 x19: ffffff8102962600 x18:
ffffffee5beb3468
[   34.367497] x17: 0000000000000001 x16: ffffffffffffffff x15:
0000000000000004
[   34.367504] x14: ffffffee5c163738 x13: 0000000000000fff x12:
0000000000000003
[   34.367512] x11: 0000000000000000 x10: 0000000000000027 x9 :
ada342fc9d5acc00
[   34.367519] x8 : ada342fc9d5acc00 x7 : 65646e75203a745f x6 :
746e756f63666572
[   34.367526] x5 : ffffffee5c3129da x4 : ffffffee5c2fc59e x3 :
0000000000000000
[   34.367533] x2 : 0000000000000000 x1 : ffffffc08341b930 x0 :
0000000000000026
[   34.367541] Call trace:
[   34.367544]  refcount_warn_saturate+0x108/0x148
[   34.367550]  v3d_submit_cl_ioctl+0x4cc/0x5e8 [v3d]
[   34.367588]  drm_ioctl_kernel+0xe0/0x120 [drm]
[   34.367767]  drm_ioctl+0x264/0x408 [drm]
[   34.367866]  __arm64_sys_ioctl+0x9c/0xe0
[   34.367877]  invoke_syscall+0x4c/0x118
[   34.367887]  el0_svc_common+0xb8/0xf0
[   34.367892]  do_el0_svc+0x28/0x40
[   34.367898]  el0_svc+0x38/0x88
[   34.367906]  el0t_64_sync_handler+0x84/0x100
[   34.367913]  el0t_64_sync+0x190/0x198
[   34.367917] ---[ end trace 0000000000000000 ]---

Best Regards,
- Maíra


Iago

El mar, 09-01-2024 a las 11:28 -0300, Maíra Canal escribió:
Currently, if `v3d_job_init()` fails (e.g. in the IGT test "bad-
in-
sync",
where we submit an invalid in-sync to the IOCTL), then we end up
with
the following NULL pointer dereference:

[   34.146279] Unable to handle kernel NULL pointer dereference
at
virtual address 0000000000000078
[   34.146301] Mem abort info:
[   34.146306]   ESR = 0x0000000096000005
[   34.146315]   EC = 0x25: DABT (current EL), IL = 32 bits
[   34.146322]   SET = 0, FnV = 0
[   34.146328]   EA = 0, S1PTW = 0
[   34.146334]   FSC = 0x05: level 1 translation fault
[   34.146340] Data abort info:
[   34.146345]   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
[   34.146351]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[   34.146357]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[   34.146366] user pgtable: 4k pages, 39-bit VAs,
pgdp=00000001232e6000
[   34.146375] [0000000000000078] pgd=0000000000000000,
p4d=0000000000000000, pud=0000000000000000
[   34.146399] Internal error: Oops: 0000000096000005 [#1]
PREEMPT
SMP
[   34.146406] Modules linked in: rfcomm snd_seq_dummy
snd_hrtimer
snd_seq snd_seq_device algif_hash aes_neon_bs aes_neon_blk
algif_skcipher af_alg bnep hid_logitech_hidpp brcmfmac_wcc
brcmfmac
brcmutil hci_uart vc4 btbcm cfg80211 bluetooth bcm2835_v4l2(C)
snd_soc_hdmi_codec binfmt_misc cec drm_display_helper
hid_logitech_dj
bcm2835_mmal_vchiq(C) drm_dma_helper drm_kms_helper
videobuf2_v4l2
raspberrypi_hwmon ecdh_generic videobuf2_vmalloc videobuf2_memops
ecc
videobuf2_common rfkill videodev libaes snd_soc_core dwc2
i2c_brcmstb
snd_pcm_dmaengine snd_bcm2835(C) i2c_bcm2835 pwm_bcm2835 snd_pcm
mc
v3d snd_timer snd gpu_sched drm_shmem_helper nvmem_rmem
uio_pdrv_genirq uio i2c_dev drm fuse dm_mod
drm_panel_orientation_quirks backlight configfs ip_tables
x_tables
ipv6
[   34.146556] CPU: 1 PID: 1890 Comm: v3d_submit_csd Tainted:
G         C         6.7.0-rc3-g49ddab089611 #68
[   34.146563] Hardware name: Raspberry Pi 4 Model B Rev 1.5 (DT)
[   34.146569] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -
SSBS
BTYPE=--)
[   34.146575] pc : drm_sched_job_cleanup+0x3c/0x190 [gpu_sched]
[   34.146611] lr : v3d_submit_csd_ioctl+0x1b4/0x460 [v3d]
[   34.146653] sp : ffffffc083cbbb80
[   34.146658] x29: ffffffc083cbbb90 x28: ffffff81035afc00 x27:
ffffffe77a641168
[   34.146668] x26: ffffff81056a8000 x25: 0000000000000058 x24:
0000000000000000
[   34.146677] x23: ffffff81065e2000 x22: ffffff81035afe00 x21:
ffffffc083cbbcf0
[   34.146686] x20: ffffff81035afe00 x19: 00000000ffffffea x18:
0000000000000000
[   34.146694] x17: 0000000000000000 x16: ffffffe7989e34b0 x15:
0000000000000000
[   34.146703] x14: 0000000004000004 x13: ffffff81035afe80 x12:
ffffffc083cb8000
[   34.146711] x11: cc57e05dfbe5ef00 x10: cc57e05dfbe5ef00 x9 :
ffffffe77a64131c
[   34.146719] x8 : 0000000000000000 x7 : 0000000000000000 x6 :
000000000000003f
[   34.146727] x5 : 0000000000000040 x4 : ffffff81fefb03f0 x3 :
ffffffc083cbba40
[   34.146736] x2 : ffffff81056a8000 x1 : ffffffe7989e35e8 x0 :
0000000000000000
[   34.146745] Call trace:
[   34.146748]  drm_sched_job_cleanup+0x3c/0x190 [gpu_sched]
[   34.146768]  v3d_submit_csd_ioctl+0x1b4/0x460 [v3d]
[   34.146791]  drm_ioctl_kernel+0xe0/0x120 [drm]
[   34.147029]  drm_ioctl+0x264/0x408 [drm]
[   34.147135]  __arm64_sys_ioctl+0x9c/0xe0
[   34.147152]  invoke_syscall+0x4c/0x118
[   34.147162]  el0_svc_common+0xb8/0xf0
[   34.147168]  do_el0_svc+0x28/0x40
[   34.147174]  el0_svc+0x38/0x88
[   34.147184]  el0t_64_sync_handler+0x84/0x100
[   34.147191]  el0t_64_sync+0x190/0x198
[   34.147201] Code: aa0003f4 f90007e8 f9401008 aa0803e0
(b8478c09)
[   34.147210] ---[ end trace 0000000000000000 ]---

This happens because we are calling `drm_sched_job_cleanup()`
twice:
once at `v3d_job_init()` and again when we call
`v3d_job_cleanup()`.

To mitigate this issue, we can return to the same approach that
we
used
to use before 464c61e76de8: deallocate the job after
`v3d_job_init()`
fails and assign it to NULL. Then, when we call
`v3d_job_cleanup()`,
job
is NULL and the function returns.

Fixes: 464c61e76de8 ("drm/v3d: Decouple job allocation from job
initiation")
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
   drivers/gpu/drm/v3d/v3d_submit.c | 35
+++++++++++++++++++++++++-----
--
   1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_submit.c
b/drivers/gpu/drm/v3d/v3d_submit.c
index fcff41dd2315..88f63d526b22 100644
--- a/drivers/gpu/drm/v3d/v3d_submit.c
+++ b/drivers/gpu/drm/v3d/v3d_submit.c
@@ -147,6 +147,13 @@ v3d_job_allocate(void **container, size_t
size)
   	return 0;
   }

+static void
+v3d_job_deallocate(void **container)
+{
+	kfree(*container);
+	*container = NULL;
+}
+
   static int
   v3d_job_init(struct v3d_dev *v3d, struct drm_file *file_priv,
   	     struct v3d_job *job, void (*free)(struct kref
*ref),
@@ -273,8 +280,10 @@ v3d_setup_csd_jobs_and_bos(struct drm_file
*file_priv,

   	ret = v3d_job_init(v3d, file_priv, &(*job)->base,
   			   v3d_job_free, args->in_sync, se,
V3D_CSD);
-	if (ret)
+	if (ret) {
+		v3d_job_deallocate((void *)job);
   		return ret;
+	}

   	ret = v3d_job_allocate((void *)clean_job,
sizeof(**clean_job));
   	if (ret)
@@ -282,8 +291,10 @@ v3d_setup_csd_jobs_and_bos(struct drm_file
*file_priv,

   	ret = v3d_job_init(v3d, file_priv, *clean_job,
   			   v3d_job_free, 0, NULL,
V3D_CACHE_CLEAN);
-	if (ret)
+	if (ret) {
+		v3d_job_deallocate((void *)clean_job);
   		return ret;
+	}

   	(*job)->args = *args;

@@ -860,8 +871,10 @@ v3d_submit_cl_ioctl(struct drm_device *dev,
void
*data,

   	ret = v3d_job_init(v3d, file_priv, &render->base,
   			   v3d_render_job_free, args-
in_sync_rcl,
&se, V3D_RENDER);
-	if (ret)
+	if (ret) {
+		v3d_job_deallocate((void *)&render);
   		goto fail;
+	}

   	render->start = args->rcl_start;
   	render->end = args->rcl_end;
@@ -874,8 +887,10 @@ v3d_submit_cl_ioctl(struct drm_device *dev,
void
*data,

   		ret = v3d_job_init(v3d, file_priv, &bin->base,
   				   v3d_job_free, args-
in_sync_bcl,
&se, V3D_BIN);
-		if (ret)
+		if (ret) {
+			v3d_job_deallocate((void *)&bin);
   			goto fail;
+		}

   		bin->start = args->bcl_start;
   		bin->end = args->bcl_end;
@@ -892,8 +907,10 @@ v3d_submit_cl_ioctl(struct drm_device *dev,
void
*data,

   		ret = v3d_job_init(v3d, file_priv, clean_job,
   				   v3d_job_free, 0, NULL,
V3D_CACHE_CLEAN);
-		if (ret)
+		if (ret) {
+			v3d_job_deallocate((void *)&clean_job);
   			goto fail;
+		}

   		last_job = clean_job;
   	} else {
@@ -1015,8 +1032,10 @@ v3d_submit_tfu_ioctl(struct drm_device
*dev,
void *data,

   	ret = v3d_job_init(v3d, file_priv, &job->base,
   			   v3d_job_free, args->in_sync, &se,
V3D_TFU);
-	if (ret)
+	if (ret) {
+		v3d_job_deallocate((void *)&job);
   		goto fail;
+	}

   	job->base.bo = kcalloc(ARRAY_SIZE(args->bo_handles),
   			       sizeof(*job->base.bo),
GFP_KERNEL);
@@ -1233,8 +1252,10 @@ v3d_submit_cpu_ioctl(struct drm_device
*dev,
void *data,

   	ret = v3d_job_init(v3d, file_priv, &cpu_job->base,
   			   v3d_job_free, 0, &se, V3D_CPU);
-	if (ret)
+	if (ret) {
+		v3d_job_deallocate((void *)&cpu_job);
   		goto fail;
+	}

   	clean_job = cpu_job->indirect_csd.clean_job;
   	csd_job = cpu_job->indirect_csd.job;
--
2.43.0








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