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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45eb6d48e23sm31544499f8f.20.2026.05.25.22.54.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 22:54:02 -0700 (PDT) From: David Carlier To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Dave Airlie , Keith Packard , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, syzbot+5d32c8bd82427f9c77cc@syzkaller.appspotmail.com, David Carlier Subject: [PATCH] drm/lease: cap object_count to avoid order > MAX_PAGE_ORDER warning Date: Tue, 26 May 2026 06:53:59 +0100 Message-ID: <20260526055359.17392-1-devnexen@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" cl->object_count comes from userspace unbounded and reaches kzalloc_objs() in fill_object_idr(); a large value trips WARN_ON_ONCE_GFP in __alloc_frozen_pages_noprof(), letting a DRM master produce a kernel splat. Bound object_count at the ioctl entry so the page allocator is never asked for an absurd order. Reported-by: syzbot+5d32c8bd82427f9c77cc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D5d32c8bd82427f9c77cc Fixes: 62884cd386b8 ("drm: Add four ioctls for managing drm mode object lea= ses [v7]") Signed-off-by: David Carlier --- drivers/gpu/drm/drm_lease.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c index 5d2cf724cbd7..bdec759187d9 100644 --- a/drivers/gpu/drm/drm_lease.c +++ b/drivers/gpu/drm/drm_lease.c @@ -466,6 +466,13 @@ static int fill_object_idr(struct drm_device *dev, return ret; } =20 +/* + * Upper bound on the number of objects a single lease can reference. + * Real workloads use a handful; this is set well above any plausible + * value to avoid kmalloc requests that would exceed MAX_PAGE_ORDER. + */ +#define DRM_MAX_LEASE_OBJECTS 4096 + /* * The master associated with the specified file will have a lease * created containing the objects specified in the ioctl structure. @@ -505,6 +512,12 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev, } =20 object_count =3D cl->object_count; + if (unlikely(object_count > DRM_MAX_LEASE_OBJECTS)) { + drm_dbg_lease(dev, "object_count %zu exceeds max %u\n", + object_count, DRM_MAX_LEASE_OBJECTS); + ret =3D -EINVAL; + goto out_lessor; + } =20 /* Handle leased objects, if any */ idr_init(&leases); --=20 2.53.0