This is a note to let you know that I've just added the patch titled drm/rockchip: Fix type promotion bug in rockchip_gem_iommu_map() to the 5.15-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-rockchip-fix-type-promotion-bug-in-rockchip_gem_.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 0636b7dca86cf5cfbceda917d3028d4ff66a952c Author: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Date: Wed Oct 11 11:01:48 2023 +0300 drm/rockchip: Fix type promotion bug in rockchip_gem_iommu_map() [ Upstream commit 6471da5ee311d53ef46eebcb7725bc94266cc0cf ] The "ret" variable is declared as ssize_t and it can hold negative error codes but the "rk_obj->base.size" variable is type size_t. This means that when we compare them, they are both type promoted to size_t and the negative error code becomes a high unsigned value and is treated as success. Add a cast to fix this. Fixes: 38f993b7c59e ("drm/rockchip: Do not use DMA mapping API if attached to IOMMU domain") Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/2bfa28b5-145d-4b9e-a18a-98819dd686ce@moroto.mountain Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c index 3b18b6a7acd3e..bde358d8309c3 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c @@ -39,7 +39,7 @@ static int rockchip_gem_iommu_map(struct rockchip_gem_object *rk_obj) ret = iommu_map_sgtable(private->domain, rk_obj->dma_addr, rk_obj->sgt, prot); - if (ret < rk_obj->base.size) { + if (ret < (ssize_t)rk_obj->base.size) { DRM_ERROR("failed to map buffer: size=%zd request_size=%zd\n", ret, rk_obj->base.size); ret = -ENOMEM;