Patch "drm/vmwgfx: Fix a null-ptr access in the cursor snooper" has been added to the 6.1-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drm/vmwgfx: Fix a null-ptr access in the cursor snooper

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-vmwgfx-fix-a-null-ptr-access-in-the-cursor-snooper.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable+bounces-203358-greg=kroah.com@vger.kernel.org Wed Dec 24 09:57:13 2025
From: Shivani Agarwal <shivani.agarwal@broadcom.com>
Date: Wed, 24 Dec 2025 00:36:52 -0800
Subject: drm/vmwgfx: Fix a null-ptr access in the cursor snooper
To: stable@vger.kernel.org, gregkh@linuxfoundation.org
Cc: zack.rusin@broadcom.com, bcm-kernel-feedback-list@broadcom.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, simona@ffwll.ch, airlied@gmail.com, brianp@vmware.com, dtor@vmware.com, airlied@redhat.com, thellstrom@vmware.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com, vamsi-krishna.brahmajosyula@broadcom.com, yin.ding@broadcom.com, tapas.kundu@broadcom.com, Kuzey Arda Bulut <kuzeyardabulut@gmail.com>, Ian Forbes <ian.forbes@broadcom.com>, Sasha Levin <sashal@kernel.org>, Shivani Agarwal <shivani.agarwal@broadcom.com>
Message-ID: <20251224083652.614902-1-shivani.agarwal@broadcom.com>

From: Zack Rusin <zack.rusin@broadcom.com>

[ Upstream commit 5ac2c0279053a2c5265d46903432fb26ae2d0da2 ]

Check that the resource which is converted to a surface exists before
trying to use the cursor snooper on it.

vmw_cmd_res_check allows explicit invalid (SVGA3D_INVALID_ID) identifiers
because some svga commands accept SVGA3D_INVALID_ID to mean "no surface",
unfortunately functions that accept the actual surfaces as objects might
(and in case of the cursor snooper, do not) be able to handle null
objects. Make sure that we validate not only the identifier (via the
vmw_cmd_res_check) but also check that the actual resource exists before
trying to do something with it.

Fixes unchecked null-ptr reference in the snooping code.

Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Fixes: c0951b797e7d ("drm/vmwgfx: Refactor resource management")
Reported-by: Kuzey Arda Bulut <kuzeyardabulut@gmail.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Ian Forbes <ian.forbes@broadcom.com>
Link: https://lore.kernel.org/r/20250917153655.1968583-1-zack.rusin@broadcom.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[Shivani: Modified to apply on v5.10.y-v6.1.y]
Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -1507,6 +1507,7 @@ static int vmw_cmd_dma(struct vmw_privat
 		       SVGA3dCmdHeader *header)
 {
 	struct vmw_buffer_object *vmw_bo = NULL;
+	struct vmw_resource *res;
 	struct vmw_surface *srf = NULL;
 	VMW_DECLARE_CMD_VAR(*cmd, SVGA3dCmdSurfaceDMA);
 	int ret;
@@ -1542,18 +1543,24 @@ static int vmw_cmd_dma(struct vmw_privat
 
 	dirty = (cmd->body.transfer == SVGA3D_WRITE_HOST_VRAM) ?
 		VMW_RES_DIRTY_SET : 0;
-	ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface,
-				dirty, user_surface_converter,
-				&cmd->body.host.sid, NULL);
+	ret = vmw_cmd_res_check(dev_priv, sw_context, vmw_res_surface, dirty,
+				user_surface_converter, &cmd->body.host.sid,
+				NULL);
 	if (unlikely(ret != 0)) {
 		if (unlikely(ret != -ERESTARTSYS))
 			VMW_DEBUG_USER("could not find surface for DMA.\n");
 		return ret;
 	}
 
-	srf = vmw_res_to_srf(sw_context->res_cache[vmw_res_surface].res);
+	res = sw_context->res_cache[vmw_res_surface].res;
+	if (!res) {
+		VMW_DEBUG_USER("Invalid DMA surface.\n");
+		return -EINVAL;
+	}
 
-	vmw_kms_cursor_snoop(srf, sw_context->fp->tfile, &vmw_bo->base, header);
+	srf = vmw_res_to_srf(res);
+	vmw_kms_cursor_snoop(srf, sw_context->fp->tfile, &vmw_bo->base,
+			     header);
 
 	return 0;
 }


Patches currently in stable-queue which might be from shivani.agarwal@broadcom.com are

queue-6.1/usb-xhci-move-link-chain-bit-quirk-checks-into-one-helper-function.patch
queue-6.1/crypto-af_alg-zero-initialize-memory-allocated-via-sock_kmalloc.patch
queue-6.1/rdma-core-fix-kasan-slab-use-after-free-read-in-ib_register_device-problem.patch
queue-6.1/drm-vmwgfx-fix-a-null-ptr-access-in-the-cursor-snooper.patch
queue-6.1/usb-xhci-apply-the-link-chain-quirk-on-nec-isoc-endpoints.patch