From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C561B27055A for ; Mon, 28 Jul 2025 13:59:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753711195; cv=none; b=bgPqbPPxY1Kz0w9S+mkHClX+kHm33rVy4iBjyCH69jmRzJw8i2W6V4p3KitKzVqIKlBXHgy/CX7c7vcrW2gwux2eSlWYYSgu1v/ahpC+V0/EL5dacTcLqbsFmWIq9huxp+zFKDW8Z2QP1MkH9UPygzBbfj45CkPS0sWoPOruyeg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753711195; c=relaxed/simple; bh=uff0+fPqv17IZjgVx89Pl+uS4ku4A+tRe5saup/XLm4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=ojDIllMjDWHBTn0/mzU4Z2TJ94PO0XcH08hhOQ3wapzGlzTO2y5DIHqB9HgQ0vs398UGbLTanMqCyarcrADfwx6WeZQIOYfC7VCHSuTWjf0kS8KO8OyUZR0IPzzgAur7x8EWJ1FY3gVVw69rHU02Lx8eCPMExn6BLw+djtSC/1o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=plTT1x7h; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="plTT1x7h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27CB2C4CEF9; Mon, 28 Jul 2025 13:59:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753711195; bh=uff0+fPqv17IZjgVx89Pl+uS4ku4A+tRe5saup/XLm4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=plTT1x7heA0nF0uyRXW/OQAXhiQnJzvooeg+EiIqLkmSGJaK+7Cimo1V7RTaNawsm U81XxjpzYzDw3BhkJyEnlId/B451HeZn8ZPS/m2kmWiY7mwKyE/WfPsnsdJ3414iC/ S69GSAwRRON7oXKISyfGiJa8CkcAvnd9JoaM1O6TnMpRXnLv4s6jKPj8ct1NwDAt2o ibWGLHCnjRU7VJQE9pT21C2rtakFBUTH0XzUYuDrVdoJ+urQ9HLr/5JFJ0rYrmyOIj D1zOr6R7ZCoHk6covT4WnJtiWEQGnDwcv3PdG1tV9a3AuBX6+S0hPQbxRIxWuqYnBS BGS5kMX8j7Eww== From: Sasha Levin To: stable@vger.kernel.org Cc: Thomas Zimmermann , Simona Vetter , =?UTF-8?q?Christian=20K=C3=B6nig?= , Zack Rusin , Sasha Levin Subject: [PATCH 6.15.y 2/2] Revert "drm/gem-shmem: Use dma_buf from GEM object instance" Date: Mon, 28 Jul 2025 09:59:47 -0400 Message-Id: <20250728135947.2330347-2-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250728135947.2330347-1-sashal@kernel.org> References: <2025072830-reveler-drop-down-d571@gregkh> <20250728135947.2330347-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Thomas Zimmermann [ Upstream commit 6d496e9569983a0d7a05be6661126d0702cf94f7 ] This reverts commit 1a148af06000e545e714fe3210af3d77ff903c11. The dma_buf field in struct drm_gem_object is not stable over the object instance's lifetime. The field becomes NULL when user space releases the final GEM handle on the buffer object. This resulted in a NULL-pointer deref. Workarounds in commit 5307dce878d4 ("drm/gem: Acquire references on GEM handles for framebuffers") and commit f6bfc9afc751 ("drm/framebuffer: Acquire internal references on GEM handles") only solved the problem partially. They especially don't work for buffer objects without a DRM framebuffer associated. Hence, this revert to going back to using .import_attach->dmabuf. v3: - cc stable Signed-off-by: Thomas Zimmermann Reviewed-by: Simona Vetter Acked-by: Christian König Acked-by: Zack Rusin Cc: # v6.15+ Link: https://lore.kernel.org/r/20250715155934.150656-7-tzimmermann@suse.de Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index de197a932852..37333aadd550 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -339,7 +339,7 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem, int ret = 0; if (drm_gem_is_imported(obj)) { - ret = dma_buf_vmap(obj->dma_buf, map); + ret = dma_buf_vmap(obj->import_attach->dmabuf, map); } else { pgprot_t prot = PAGE_KERNEL; @@ -399,7 +399,7 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem, struct drm_gem_object *obj = &shmem->base; if (drm_gem_is_imported(obj)) { - dma_buf_vunmap(obj->dma_buf, map); + dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { dma_resv_assert_held(shmem->base.resv); -- 2.39.5