--- /dev/null
+From 6e64d6b3a3c39655de56682ec83e894978d23412 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <mcanal@igalia.com>
+Date: Wed, 22 Jan 2025 22:24:03 -0300
+Subject: drm/v3d: Assign job pointer to NULL before signaling the fence
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Maíra Canal <mcanal@igalia.com>
+
+commit 6e64d6b3a3c39655de56682ec83e894978d23412 upstream.
+
+In commit e4b5ccd392b9 ("drm/v3d: Ensure job pointer is set to NULL
+after job completion"), we introduced a change to assign the job pointer
+to NULL after completing a job, indicating job completion.
+
+However, this approach created a race condition between the DRM
+scheduler workqueue and the IRQ execution thread. As soon as the fence is
+signaled in the IRQ execution thread, a new job starts to be executed.
+This results in a race condition where the IRQ execution thread sets the
+job pointer to NULL simultaneously as the `run_job()` function assigns
+a new job to the pointer.
+
+This race condition can lead to a NULL pointer dereference if the IRQ
+execution thread sets the job pointer to NULL after `run_job()` assigns
+it to the new job. When the new job completes and the GPU emits an
+interrupt, `v3d_irq()` is triggered, potentially causing a crash.
+
+[ 466.310099] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000c0
+[ 466.318928] Mem abort info:
+[ 466.321723] ESR = 0x0000000096000005
+[ 466.325479] EC = 0x25: DABT (current EL), IL = 32 bits
+[ 466.330807] SET = 0, FnV = 0
+[ 466.333864] EA = 0, S1PTW = 0
+[ 466.337010] FSC = 0x05: level 1 translation fault
+[ 466.341900] Data abort info:
+[ 466.344783] ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
+[ 466.350285] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
+[ 466.355350] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
+[ 466.360677] user pgtable: 4k pages, 39-bit VAs, pgdp=0000000089772000
+[ 466.367140] [00000000000000c0] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
+[ 466.375875] Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
+[ 466.382163] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device algif_hash algif_skcipher af_alg bnep binfmt_misc vc4 snd_soc_hdmi_codec drm_display_helper cec brcmfmac_wcc spidev rpivid_hevc(C) drm_client_lib brcmfmac hci_uart drm_dma_helper pisp_be btbcm brcmutil snd_soc_core aes_ce_blk v4l2_mem2mem bluetooth aes_ce_cipher snd_compress videobuf2_dma_contig ghash_ce cfg80211 gf128mul snd_pcm_dmaengine videobuf2_memops ecdh_generic sha2_ce ecc videobuf2_v4l2 snd_pcm v3d sha256_arm64 rfkill videodev snd_timer sha1_ce libaes gpu_sched snd videobuf2_common sha1_generic drm_shmem_helper mc rp1_pio drm_kms_helper raspberrypi_hwmon spi_bcm2835 gpio_keys i2c_brcmstb rp1 raspberrypi_gpiomem rp1_mailbox rp1_adc nvmem_rmem uio_pdrv_genirq uio i2c_dev drm ledtrig_pattern drm_panel_orientation_quirks backlight fuse dm_mod ip_tables x_tables ipv6
+[ 466.458429] CPU: 0 UID: 1000 PID: 2008 Comm: chromium Tainted: G C 6.13.0-v8+ #18
+[ 466.467336] Tainted: [C]=CRAP
+[ 466.470306] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
+[ 466.476157] pstate: 404000c9 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
+[ 466.483143] pc : v3d_irq+0x118/0x2e0 [v3d]
+[ 466.487258] lr : __handle_irq_event_percpu+0x60/0x228
+[ 466.492327] sp : ffffffc080003ea0
+[ 466.495646] x29: ffffffc080003ea0 x28: ffffff80c0c94200 x27: 0000000000000000
+[ 466.502807] x26: ffffffd08dd81d7b x25: ffffff80c0c94200 x24: ffffff8003bdc200
+[ 466.509969] x23: 0000000000000001 x22: 00000000000000a7 x21: 0000000000000000
+[ 466.517130] x20: ffffff8041bb0000 x19: 0000000000000001 x18: 0000000000000000
+[ 466.524291] x17: ffffffafadfb0000 x16: ffffffc080000000 x15: 0000000000000000
+[ 466.531452] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
+[ 466.538613] x11: 0000000000000000 x10: 0000000000000000 x9 : ffffffd08c527eb0
+[ 466.545777] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
+[ 466.552941] x5 : ffffffd08c4100d0 x4 : ffffffafadfb0000 x3 : ffffffc080003f70
+[ 466.560102] x2 : ffffffc0829e8058 x1 : 0000000000000001 x0 : 0000000000000000
+[ 466.567263] Call trace:
+[ 466.569711] v3d_irq+0x118/0x2e0 [v3d] (P)
+[ 466.573826] __handle_irq_event_percpu+0x60/0x228
+[ 466.578546] handle_irq_event+0x54/0xb8
+[ 466.582391] handle_fasteoi_irq+0xac/0x240
+[ 466.586498] generic_handle_domain_irq+0x34/0x58
+[ 466.591128] gic_handle_irq+0x48/0xd8
+[ 466.594798] call_on_irq_stack+0x24/0x58
+[ 466.598730] do_interrupt_handler+0x88/0x98
+[ 466.602923] el0_interrupt+0x44/0xc0
+[ 466.606508] __el0_irq_handler_common+0x18/0x28
+[ 466.611050] el0t_64_irq_handler+0x10/0x20
+[ 466.615156] el0t_64_irq+0x198/0x1a0
+[ 466.618740] Code: 52800035 3607faf3 f9442e80 52800021 (f9406018)
+[ 466.624853] ---[ end trace 0000000000000000 ]---
+[ 466.629483] Kernel panic - not syncing: Oops: Fatal exception in interrupt
+[ 466.636384] SMP: stopping secondary CPUs
+[ 466.640320] Kernel Offset: 0x100c400000 from 0xffffffc080000000
+[ 466.646259] PHYS_OFFSET: 0x0
+[ 466.649141] CPU features: 0x100,00000170,00901250,0200720b
+[ 466.654644] Memory Limit: none
+[ 466.657706] ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---
+
+Fix the crash by assigning the job pointer to NULL before signaling the
+fence. This ensures that the job pointer is cleared before any new job
+starts execution, preventing the race condition and the NULL pointer
+dereference crash.
+
+Cc: stable@vger.kernel.org
+Fixes: e4b5ccd392b9 ("drm/v3d: Ensure job pointer is set to NULL after job completion")
+Signed-off-by: Maíra Canal <mcanal@igalia.com>
+Reviewed-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
+Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
+Tested-by: Phil Elwell <phil@raspberrypi.com>
+Link: https://patchwork.freedesktop.org/patch/msgid/20250123012403.20447-1-mcanal@igalia.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/gpu/drm/v3d/v3d_irq.c | 16 ++++++++++++----
+ 1 file changed, 12 insertions(+), 4 deletions(-)
+
+--- a/drivers/gpu/drm/v3d/v3d_irq.c
++++ b/drivers/gpu/drm/v3d/v3d_irq.c
+@@ -102,8 +102,10 @@ v3d_irq(int irq, void *arg)
+ to_v3d_fence(v3d->bin_job->base.irq_fence);
+
+ trace_v3d_bcl_irq(&v3d->drm, fence->seqno);
+- dma_fence_signal(&fence->base);
++
+ v3d->bin_job = NULL;
++ dma_fence_signal(&fence->base);
++
+ status = IRQ_HANDLED;
+ }
+
+@@ -112,8 +114,10 @@ v3d_irq(int irq, void *arg)
+ to_v3d_fence(v3d->render_job->base.irq_fence);
+
+ trace_v3d_rcl_irq(&v3d->drm, fence->seqno);
+- dma_fence_signal(&fence->base);
++
+ v3d->render_job = NULL;
++ dma_fence_signal(&fence->base);
++
+ status = IRQ_HANDLED;
+ }
+
+@@ -122,8 +126,10 @@ v3d_irq(int irq, void *arg)
+ to_v3d_fence(v3d->csd_job->base.irq_fence);
+
+ trace_v3d_csd_irq(&v3d->drm, fence->seqno);
+- dma_fence_signal(&fence->base);
++
+ v3d->csd_job = NULL;
++ dma_fence_signal(&fence->base);
++
+ status = IRQ_HANDLED;
+ }
+
+@@ -159,8 +165,10 @@ v3d_hub_irq(int irq, void *arg)
+ to_v3d_fence(v3d->tfu_job->base.irq_fence);
+
+ trace_v3d_tfu_irq(&v3d->drm, fence->seqno);
+- dma_fence_signal(&fence->base);
++
+ v3d->tfu_job = NULL;
++ dma_fence_signal(&fence->base);
++
+ status = IRQ_HANDLED;
+ }
+