[PATCH AUTOSEL 6.1 16/34] drm/amdkfd: Fix BO offset for multi-VMA page migration

[PATCH AUTOSEL 6.1 16/34] drm/amdkfd: Fix BO offset for multi-VMA page migration

[Sasha Levin]

From: Xiaogang Chen <Xiaogang.Chen@amd.com>

[ Upstream commit b4ee9606378bb9520c94d8b96f0305c3696f5c29 ]

svm_migrate_ram_to_vram migrates a prange from sys ram to vram. The prange may
cross multiple vma. Need remember current dst vram offset in the TTM resource for
each migration.

v2: squash in warning fix (Alex)

Signed-off-by: Xiaogang Chen <Xiaogang.Chen@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 22b077ac9a196..fad500dd224d8 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -295,7 +295,7 @@ static unsigned long svm_migrate_unsuccessful_pages(struct migrate_vma *migrate)
 static int
 svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 			 struct migrate_vma *migrate, struct dma_fence **mfence,
-			 dma_addr_t *scratch)
+			 dma_addr_t *scratch, uint64_t ttm_res_offset)
 {
 	uint64_t npages = migrate->npages;
 	struct device *dev = adev->dev;
@@ -305,8 +305,8 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 	uint64_t i, j;
 	int r;
 
-	pr_debug("svms 0x%p [0x%lx 0x%lx]\n", prange->svms, prange->start,
-		 prange->last);
+	pr_debug("svms 0x%p [0x%lx 0x%lx 0x%llx]\n", prange->svms, prange->start,
+		 prange->last, ttm_res_offset);
 
 	src = scratch;
 	dst = (uint64_t *)(scratch + npages);
@@ -317,7 +317,7 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 		goto out;
 	}
 
-	amdgpu_res_first(prange->ttm_res, prange->offset << PAGE_SHIFT,
+	amdgpu_res_first(prange->ttm_res, ttm_res_offset,
 			 npages << PAGE_SHIFT, &cursor);
 	for (i = j = 0; i < npages; i++) {
 		struct page *spage;
@@ -404,7 +404,7 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 static long
 svm_migrate_vma_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 			struct vm_area_struct *vma, uint64_t start,
-			uint64_t end, uint32_t trigger)
+			uint64_t end, uint32_t trigger, uint64_t ttm_res_offset)
 {
 	struct kfd_process *p = container_of(prange->svms, struct kfd_process, svms);
 	uint64_t npages = (end - start) >> PAGE_SHIFT;
@@ -457,7 +457,7 @@ svm_migrate_vma_to_vram(struct amdgpu_device *adev, struct svm_range *prange,
 	else
 		pr_debug("0x%lx pages migrated\n", cpages);
 
-	r = svm_migrate_copy_to_vram(adev, prange, &migrate, &mfence, scratch);
+	r = svm_migrate_copy_to_vram(adev, prange, &migrate, &mfence, scratch, ttm_res_offset);
 	migrate_vma_pages(&migrate);
 
 	pr_debug("successful/cpages/npages 0x%lx/0x%lx/0x%lx\n",
@@ -505,6 +505,7 @@ svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
 	unsigned long addr, start, end;
 	struct vm_area_struct *vma;
 	struct amdgpu_device *adev;
+	uint64_t ttm_res_offset;
 	unsigned long cpages = 0;
 	long r = 0;
 
@@ -525,6 +526,7 @@ svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
 
 	start = prange->start << PAGE_SHIFT;
 	end = (prange->last + 1) << PAGE_SHIFT;
+	ttm_res_offset = prange->offset << PAGE_SHIFT;
 
 	for (addr = start; addr < end;) {
 		unsigned long next;
@@ -534,13 +536,14 @@ svm_migrate_ram_to_vram(struct svm_range *prange, uint32_t best_loc,
 			break;
 
 		next = min(vma->vm_end, end);
-		r = svm_migrate_vma_to_vram(adev, prange, vma, addr, next, trigger);
+		r = svm_migrate_vma_to_vram(adev, prange, vma, addr, next, trigger, ttm_res_offset);
 		if (r < 0) {
 			pr_debug("failed %ld to migrate\n", r);
 			break;
 		} else {
 			cpages += r;
 		}
+		ttm_res_offset += next - addr;
 		addr = next;
 	}
 
-- 
2.39.2

[PATCH AUTOSEL 6.1 17/34] drm/amdkfd: fix a potential double free in pqm_create_queue

[Sasha Levin]

From: Chia-I Wu <olvaffe@gmail.com>

[ Upstream commit b2ca5c5d416b4e72d1e9d0293fc720e2d525fd42 ]

Set *q to NULL on errors, otherwise pqm_create_queue would free it
again.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.c
index 5137476ec18e6..4236539d9f932 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process_queue_manager.c
@@ -218,8 +218,8 @@ static int init_user_queue(struct process_queue_manager *pqm,
 	return 0;
 
 cleanup:
-	if (dev->shared_resources.enable_mes)
-		uninit_queue(*q);
+	uninit_queue(*q);
+	*q = NULL;
 	return retval;
 }
 
-- 
2.39.2

[PATCH AUTOSEL 6.1 18/34] drm/amdkfd: fix potential kgd_mem UAFs

[Sasha Levin]

From: Chia-I Wu <olvaffe@gmail.com>

[ Upstream commit 9da050b0d9e04439d225a2ec3044af70cdfb3933 ]

kgd_mem pointers returned by kfd_process_device_translate_handle are
only guaranteed to be valid while p->mutex is held. As soon as the mutex
is unlocked, another thread can free the BO.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index f79b8e964140e..e191d38f3da62 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1298,14 +1298,14 @@ static int kfd_ioctl_map_memory_to_gpu(struct file *filep,
 		args->n_success = i+1;
 	}
 
-	mutex_unlock(&p->mutex);
-
 	err = amdgpu_amdkfd_gpuvm_sync_memory(dev->adev, (struct kgd_mem *) mem, true);
 	if (err) {
 		pr_debug("Sync memory failed, wait interrupted by user signal\n");
 		goto sync_memory_failed;
 	}
 
+	mutex_unlock(&p->mutex);
+
 	/* Flush TLBs after waiting for the page table updates to complete */
 	for (i = 0; i < args->n_devices; i++) {
 		peer_pdd = kfd_process_device_data_by_id(p, devices_arr[i]);
@@ -1321,9 +1321,9 @@ static int kfd_ioctl_map_memory_to_gpu(struct file *filep,
 bind_process_to_device_failed:
 get_mem_obj_from_handle_failed:
 map_memory_to_gpu_failed:
+sync_memory_failed:
 	mutex_unlock(&p->mutex);
 copy_from_user_failed:
-sync_memory_failed:
 	kfree(devices_arr);
 
 	return err;
@@ -1337,6 +1337,7 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
 	void *mem;
 	long err = 0;
 	uint32_t *devices_arr = NULL, i;
+	bool flush_tlb;
 
 	if (!args->n_devices) {
 		pr_debug("Device IDs array empty\n");
@@ -1389,16 +1390,19 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
 		}
 		args->n_success = i+1;
 	}
-	mutex_unlock(&p->mutex);
 
-	if (kfd_flush_tlb_after_unmap(pdd->dev)) {
+	flush_tlb = kfd_flush_tlb_after_unmap(pdd->dev);
+	if (flush_tlb) {
 		err = amdgpu_amdkfd_gpuvm_sync_memory(pdd->dev->adev,
 				(struct kgd_mem *) mem, true);
 		if (err) {
 			pr_debug("Sync memory failed, wait interrupted by user signal\n");
 			goto sync_memory_failed;
 		}
+	}
+	mutex_unlock(&p->mutex);
 
+	if (flush_tlb) {
 		/* Flush TLBs after waiting for the page table updates to complete */
 		for (i = 0; i < args->n_devices; i++) {
 			peer_pdd = kfd_process_device_data_by_id(p, devices_arr[i]);
@@ -1414,9 +1418,9 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
 bind_process_to_device_failed:
 get_mem_obj_from_handle_failed:
 unmap_memory_from_gpu_failed:
+sync_memory_failed:
 	mutex_unlock(&p->mutex);
 copy_from_user_failed:
-sync_memory_failed:
 	kfree(devices_arr);
 	return err;
 }
-- 
2.39.2

[PATCH AUTOSEL 6.1 22/34] fbdev: tgafb: Fix potential divide by zero

[Sasha Levin]

From: Wei Chen <harperchen1110@gmail.com>

[ Upstream commit f90bd245de82c095187d8c2cabb8b488a39eaecc ]

fb_set_var would by called when user invokes ioctl with cmd
FBIOPUT_VSCREENINFO. User-provided data would finally reach
tgafb_check_var. In case var->pixclock is assigned to zero,
divide by zero would occur when checking whether reciprocal
of var->pixclock is too high.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to tgafb_check_var. We believe it could also be triggered
in driver tgafb from user site.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/tgafb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/tgafb.c b/drivers/video/fbdev/tgafb.c
index 251dbd282f5ed..84d5daef97666 100644
--- a/drivers/video/fbdev/tgafb.c
+++ b/drivers/video/fbdev/tgafb.c
@@ -173,6 +173,9 @@ tgafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
 	struct tga_par *par = (struct tga_par *)info->par;
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (par->tga_type == TGA_TYPE_8PLANE) {
 		if (var->bits_per_pixel != 8)
 			return -EINVAL;
-- 
2.39.2

[PATCH AUTOSEL 6.1 26/34] drm/amdkfd: Fixed kfd_process cleanup on module exit.

[Sasha Levin]

From: David Belanger <david.belanger@amd.com>

[ Upstream commit 20bc9f76b6a2455c6b54b91ae7634f147f64987f ]

Handle case when module is unloaded (kfd_exit) before a process space
(mm_struct) is released.

v2: Fixed potential race conditions by removing all kfd_process from
the process table first, then working on releasing the resources.

v3: Fixed loop element access / synchronization.  Fixed extra empty lines.

Signed-off-by: David Belanger <david.belanger@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_module.c  |  1 +
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  1 +
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 67 +++++++++++++++++++++---
 3 files changed, 62 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
index 09b966dc37681..aee2212e52f69 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c
@@ -77,6 +77,7 @@ static int kfd_init(void)
 
 static void kfd_exit(void)
 {
+	kfd_cleanup_processes();
 	kfd_debugfs_fini();
 	kfd_process_destroy_wq();
 	kfd_procfs_shutdown();
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index bf610e3b683bb..6d6588b9beed7 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -928,6 +928,7 @@ bool kfd_dev_is_large_bar(struct kfd_dev *dev);
 
 int kfd_process_create_wq(void);
 void kfd_process_destroy_wq(void);
+void kfd_cleanup_processes(void);
 struct kfd_process *kfd_create_process(struct file *filep);
 struct kfd_process *kfd_get_process(const struct task_struct *task);
 struct kfd_process *kfd_lookup_process_by_pasid(u32 pasid);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index dd351105c1bcf..7f68d51541e8e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -1167,6 +1167,17 @@ static void kfd_process_free_notifier(struct mmu_notifier *mn)
 	kfd_unref_process(container_of(mn, struct kfd_process, mmu_notifier));
 }
 
+static void kfd_process_notifier_release_internal(struct kfd_process *p)
+{
+	cancel_delayed_work_sync(&p->eviction_work);
+	cancel_delayed_work_sync(&p->restore_work);
+
+	/* Indicate to other users that MM is no longer valid */
+	p->mm = NULL;
+
+	mmu_notifier_put(&p->mmu_notifier);
+}
+
 static void kfd_process_notifier_release(struct mmu_notifier *mn,
 					struct mm_struct *mm)
 {
@@ -1181,17 +1192,22 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn,
 		return;
 
 	mutex_lock(&kfd_processes_mutex);
+	/*
+	 * Do early return if table is empty.
+	 *
+	 * This could potentially happen if this function is called concurrently
+	 * by mmu_notifier and by kfd_cleanup_pocesses.
+	 *
+	 */
+	if (hash_empty(kfd_processes_table)) {
+		mutex_unlock(&kfd_processes_mutex);
+		return;
+	}
 	hash_del_rcu(&p->kfd_processes);
 	mutex_unlock(&kfd_processes_mutex);
 	synchronize_srcu(&kfd_processes_srcu);
 
-	cancel_delayed_work_sync(&p->eviction_work);
-	cancel_delayed_work_sync(&p->restore_work);
-
-	/* Indicate to other users that MM is no longer valid */
-	p->mm = NULL;
-
-	mmu_notifier_put(&p->mmu_notifier);
+	kfd_process_notifier_release_internal(p);
 }
 
 static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = {
@@ -1200,6 +1216,43 @@ static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = {
 	.free_notifier = kfd_process_free_notifier,
 };
 
+/*
+ * This code handles the case when driver is being unloaded before all
+ * mm_struct are released.  We need to safely free the kfd_process and
+ * avoid race conditions with mmu_notifier that might try to free them.
+ *
+ */
+void kfd_cleanup_processes(void)
+{
+	struct kfd_process *p;
+	struct hlist_node *p_temp;
+	unsigned int temp;
+	HLIST_HEAD(cleanup_list);
+
+	/*
+	 * Move all remaining kfd_process from the process table to a
+	 * temp list for processing.   Once done, callback from mmu_notifier
+	 * release will not see the kfd_process in the table and do early return,
+	 * avoiding double free issues.
+	 */
+	mutex_lock(&kfd_processes_mutex);
+	hash_for_each_safe(kfd_processes_table, temp, p_temp, p, kfd_processes) {
+		hash_del_rcu(&p->kfd_processes);
+		synchronize_srcu(&kfd_processes_srcu);
+		hlist_add_head(&p->kfd_processes, &cleanup_list);
+	}
+	mutex_unlock(&kfd_processes_mutex);
+
+	hlist_for_each_entry_safe(p, p_temp, &cleanup_list, kfd_processes)
+		kfd_process_notifier_release_internal(p);
+
+	/*
+	 * Ensures that all outstanding free_notifier get called, triggering
+	 * the release of the kfd_process struct.
+	 */
+	mmu_notifier_synchronize();
+}
+
 static int kfd_process_init_cwsr_apu(struct kfd_process *p, struct file *filep)
 {
 	unsigned long  offset;
-- 
2.39.2

[PATCH AUTOSEL 6.1 28/34] fbdev: nvidia: Fix potential divide by zero

[Sasha Levin]

From: Wei Chen <harperchen1110@gmail.com>

[ Upstream commit 92e2a00f2987483e1f9253625828622edd442e61 ]

variable var->pixclock can be set by user. In case it
equals to zero, divide by zero would occur in nvidiafb_set_par.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to nvidia_check_var and nvidiafb_set_par. We believe it
could also be triggered in driver nvidia from user site.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/nvidia/nvidia.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
index a6c3bc2222463..1b8904824ad83 100644
--- a/drivers/video/fbdev/nvidia/nvidia.c
+++ b/drivers/video/fbdev/nvidia/nvidia.c
@@ -764,6 +764,8 @@ static int nvidiafb_check_var(struct fb_var_screeninfo *var,
 	int pitch, err = 0;
 
 	NVTRACE_ENTER();
+	if (!var->pixclock)
+		return -EINVAL;
 
 	var->transp.offset = 0;
 	var->transp.length = 0;
-- 
2.39.2

[PATCH AUTOSEL 6.1 29/34] fbdev: intelfb: Fix potential divide by zero

[Sasha Levin]

From: Wei Chen <harperchen1110@gmail.com>

[ Upstream commit d823685486a3446d061fed7c7d2f80af984f119a ]

Variable var->pixclock is controlled by user and can be assigned
to zero. Without proper check, divide by zero would occur in
intelfbhw_validate_mode and intelfbhw_mode_to_hw.

Error out if var->pixclock is zero.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/intelfb/intelfbdrv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/intelfb/intelfbdrv.c b/drivers/video/fbdev/intelfb/intelfbdrv.c
index d4a2891a9a7ac..a93dd531d00df 100644
--- a/drivers/video/fbdev/intelfb/intelfbdrv.c
+++ b/drivers/video/fbdev/intelfb/intelfbdrv.c
@@ -1219,6 +1219,9 @@ static int intelfb_check_var(struct fb_var_screeninfo *var,
 
 	dinfo = GET_DINFO(info);
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	/* update the pitch */
 	if (intelfbhw_validate_mode(dinfo, var) != 0)
 		return -EINVAL;
-- 
2.39.2

[PATCH AUTOSEL 6.1 30/34] fbdev: lxfb: Fix potential divide by zero

[Sasha Levin]

From: Wei Chen <harperchen1110@gmail.com>

[ Upstream commit 61ac4b86a4c047c20d5cb423ddd87496f14d9868 ]

var->pixclock can be assigned to zero by user. Without proper
check, divide by zero would occur in lx_set_clock.

Error out if var->pixclock is zero.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/geode/lxfb_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/geode/lxfb_core.c b/drivers/video/fbdev/geode/lxfb_core.c
index 9d26592dbfce9..41fda498406c1 100644
--- a/drivers/video/fbdev/geode/lxfb_core.c
+++ b/drivers/video/fbdev/geode/lxfb_core.c
@@ -235,6 +235,9 @@ static void get_modedb(struct fb_videomode **modedb, unsigned int *size)
 
 static int lxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (var->xres > 1920 || var->yres > 1440)
 		return -EINVAL;
 
-- 
2.39.2

[PATCH AUTOSEL 6.1 31/34] fbdev: au1200fb: Fix potential divide by zero

[Sasha Levin]

From: Wei Chen <harperchen1110@gmail.com>

[ Upstream commit 44a3b36b42acfc433aaaf526191dd12fbb919fdb ]

var->pixclock can be assigned to zero by user. Without
proper check, divide by zero would occur when invoking
macro PICOS2KHZ in au1200fb_fb_check_var.

Error out if var->pixclock is zero.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/video/fbdev/au1200fb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 81c3154544287..b6b22fa4a8a01 100644
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c
@@ -1040,6 +1040,9 @@ static int au1200fb_fb_check_var(struct fb_var_screeninfo *var,
 	u32 pixclock;
 	int screen_size, plane;
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	plane = fbdev->plane;
 
 	/* Make sure that the mode respect all LCD controller and
-- 
2.39.2