FAILED: patch "[PATCH] drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE," failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 39bc27bd688066a63e56f7f64ad34fae03fbe3b8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024061944-culture-agreeable-2b0e@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

39bc27bd6880 ("drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE, MAP_PRIVATE)")
21aa27ddc582 ("drm/shmem-helper: Switch to reservation lock")
67fe7487fe89 ("drm/shmem-helper: Don't use vmap_use_count for dma-bufs")
3f6a1e22fae9 ("drm/shmem-helper: Switch to use drm_* debug helpers")
aa8c85affe3f ("drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages_sgt()")
09bf649a7457 ("drm/shmem-helper: Avoid vm_open error paths")
24013314be6e ("drm/shmem-helper: Remove errant put in error path")
df4aaf015775 ("drm/shmem-helper: Add missing vunmap on error")
7938f4218168 ("dma-buf-map: Rename to iosys-map")
ae710a458f0a ("drm: Replace kernel.h with the necessary inclusions")
c47160d8edcd ("drm/mipi-dbi: Remove dependency on GEM CMA helper library")
e580ea25c08d ("drm/cma-helper: Pass GEM CMA object in public interfaces")
05b1de51df07 ("drm/cma-helper: Export dedicated wrappers for GEM object functions")
d0c4e34db0b0 ("drm/cma-helper: Move driver and file ops to the end of header")
6a2d2ddf2c34 ("drm: Move nomodeset kernel parameter to the DRM subsystem")
d76f25d66ec8 ("drm/vboxvideo: Drop CONFIG_VGA_CONSOLE guard to call vgacon_text_force()")
35f7775f81bf ("drm: Don't print messages if drivers are disabled due nomodeset")
a713ca234ea9 ("Merge drm/drm-next into drm-misc-next")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 39bc27bd688066a63e56f7f64ad34fae03fbe3b8 Mon Sep 17 00:00:00 2001
From: "Wachowski, Karol" <karol.wachowski@intel.com>
Date: Mon, 20 May 2024 12:05:14 +0200
Subject: [PATCH] drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE,
 MAP_PRIVATE)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Lack of check for copy-on-write (COW) mapping in drm_gem_shmem_mmap
allows users to call mmap with PROT_WRITE and MAP_PRIVATE flag
causing a kernel panic due to BUG_ON in vmf_insert_pfn_prot:
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));

Return -EINVAL early if COW mapping is detected.

This bug affects all drm drivers using default shmem helpers.
It can be reproduced by this simple example:
void *ptr = mmap(0, size, PROT_WRITE, MAP_PRIVATE, fd, mmap_offset);
ptr[0] = 0;

Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Wachowski, Karol <karol.wachowski@intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240520100514.925681-1-jacek.lawrynowicz@linux.intel.com

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index e435f986cd13..1ff0678be7c7 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -610,6 +610,9 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
 		return ret;
 	}
 
+	if (is_cow_mapping(vma->vm_flags))
+		return -EINVAL;
+
 	dma_resv_lock(shmem->base.resv, NULL);
 	ret = drm_gem_shmem_get_pages(shmem);
 	dma_resv_unlock(shmem->base.resv);