linux-kernel - [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

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Date:   Wed, 14 Jun 2023 10:15:28 -0600
From:   Jeffrey Hugo <quic_jhugo@...cinc.com>
To:     <quic_carlv@...cinc.com>, <quic_pkanojiy@...cinc.com>,
        <christian.koenig@....com>, <sukrut.bellary@...ux.com>,
        <sumit.semwal@...aro.org>
CC:     <ogabbay@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <kernel-janitors@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        <linaro-mm-sig@...ts.linaro.org>, <linux-media@...r.kernel.org>,
        Jeffrey Hugo <quic_jhugo@...cinc.com>
Subject: [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

From: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@...cinc.com>

smatch warning:
	drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error:
		dereferencing freed memory 'obj->import_attach'

obj->import_attach is detached and freed using dma_buf_detach().
But used after free to decrease the dmabuf ref count using
dma_buf_put().

drm_prime_gem_destroy() handles this issue and performs the proper clean
up instead of open coding it in the driver.

Fixes: ff13be830333 ("accel/qaic: Add datapath")
Reported-by: Sukrut Bellary <sukrut.bellary@...ux.com>
Closes: https://lore.kernel.org/all/20230610021200.377452-1-sukrut.bellary@linux.com/
Suggested-by: Christian König <christian.koenig@....com>
Signed-off-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@...cinc.com>
Reviewed-by: Carl Vanderlip <quic_carlv@...cinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@...cinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@...cinc.com>
---
 drivers/accel/qaic/qaic_data.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index e42c1f9ffff8..e9a1cb779b30 100644
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -23,6 +23,7 @@
 #include <linux/wait.h>
 #include <drm/drm_file.h>
 #include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
 #include <drm/drm_print.h>
 #include <uapi/drm/qaic_accel.h>
 
@@ -616,8 +617,7 @@ static void qaic_free_object(struct drm_gem_object *obj)
 
 	if (obj->import_attach) {
 		/* DMABUF/PRIME Path */
-		dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach);
-		dma_buf_put(obj->import_attach->dmabuf);
+		drm_prime_gem_destroy(obj, NULL);
 	} else {
 		/* Private buffer allocation path */
 		qaic_free_sgt(bo->sgt);
-- 
2.40.1