Commit afe656d5 authored by Wachowski, Karol's avatar Wachowski, Karol Committed by Pu Lehui
Browse files

drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE, MAP_PRIVATE) 

mainline inclusion
from mainline-v6.10-rc2
commit 39bc27bd688066a63e56f7f64ad34fae03fbe3b8
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACS4Z
CVE: CVE-2024-39497

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=39bc27bd6880



--------------------------------

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: 2194a63a ("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: default avatarWachowski, Karol <karol.wachowski@intel.com>
Signed-off-by: default avatarJacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240520100514.925681-1-jacek.lawrynowicz@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Conflicts:
	drivers/gpu/drm/drm_gem_shmem_helper.c
[The conflicts were due to not merge commit 21aa27dd and 97a7e473]
Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
parent 2630e077

drivers/gpu/drm/drm_gem_shmem_helper.c

+5 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#include <drm/drm_prime.h>

#include <drm/drm_print.h>



#include "../../../mm/internal.h"	/* is_cow_mapping() */



/**

 * DOC: overview

 *
@@ -630,6 +632,9 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) 
		return ret;

	}



	if (is_cow_mapping(vma->vm_flags))

		return -EINVAL;



	shmem = to_drm_gem_shmem_obj(obj);



	ret = drm_gem_shmem_get_pages(shmem);