Hi sean,
On 05/25/2017 11:30 PM, Sean Paul wrote:
On Tue, May 23, 2017 at 02:39:43PM +0800, Jeffy Chen wrote:
The system would crash when trying to alloc zero sized gem buffer:
[ 6.712435] Unable to handle kernel NULL pointer dereference at virtual address 00000010 <--ZERO_SIZE_PTR
...
[ 6.757502] PC is at sg_alloc_table_from_pages+0x170/0x1ec
It's unfortunate that you didn't include the entire stack trace. From code
inspection, it seems like the 0 size comes from the fb_probe path? Is there
somewhere in the helpers that you could check the mode is sane so all drivers
can benefit?
hmm, sorry, i was testing it on chromeos 4.4 kernel, it turns out that
we have a custom ioctl for userspace to create gem buffer(the same as
exynos drm), which might get the the 0 size.
but on upstream kernel, it could only be called by dump_create, and the
drm_mode_create_dumb_ioctl already did the size check.
will resent this patch, and rewrite the commit message, thanx.
Sean
Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index df9e570..8917922 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -315,6 +315,11 @@ struct rockchip_gem_object *
struct drm_gem_object *obj;
int ret;
+ if (!size) {
+ DRM_ERROR("gem buffer size is zero\n");
+ return ERR_PTR(-EINVAL);
+ }
+
size = round_up(size, PAGE_SIZE);
rk_obj = kzalloc(sizeof(*rk_obj), GFP_KERNEL);
--
2.1.4
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