This is a note to let you know that I've just added the patch titled
drm/crtc: Fix uninit-value bug in drm_mode_setcrtc
to the 6.6-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-crtc-fix-uninit-value-bug-in-drm_mode_setcrtc.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5b3d73a001a44deadaadb682e29e0efd83fddf3a
Author: Ziqi Zhao <astrajoan@xxxxxxxxx>
Date: Fri Jul 21 09:14:46 2023 -0700
drm/crtc: Fix uninit-value bug in drm_mode_setcrtc
[ Upstream commit 3823119b9c2b5f9e9b760336f75bc989b805cde6 ]
The connector_set contains uninitialized values when allocated with
kmalloc_array. However, in the "out" branch, the logic assumes that any
element in connector_set would be equal to NULL if failed to
initialize, which causes the bug reported by Syzbot. The fix is to use
an extra variable to keep track of how many connectors are initialized
indeed, and use that variable to decrease any refcounts in the "out"
branch.
Reported-by: syzbot+4fad2e57beb6397ab2fc@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ziqi Zhao <astrajoan@xxxxxxxxx>
Reported-and-tested-by: syzbot+4fad2e57beb6397ab2fc@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230721161446.8602-1-astrajoan@xxxxxxxxx
Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index df9bf3c9206e..d718c17ab1e9 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -715,8 +715,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
struct drm_mode_set set;
uint32_t __user *set_connectors_ptr;
struct drm_modeset_acquire_ctx ctx;
- int ret;
- int i;
+ int ret, i, num_connectors;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
@@ -851,6 +850,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
goto out;
}
+ num_connectors = 0;
for (i = 0; i < crtc_req->count_connectors; i++) {
connector_set[i] = NULL;
set_connectors_ptr = (uint32_t __user *)(unsigned long)crtc_req->set_connectors_ptr;
@@ -871,6 +871,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
connector->name);
connector_set[i] = connector;
+ num_connectors++;
}
}
@@ -879,7 +880,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
set.y = crtc_req->y;
set.mode = mode;
set.connectors = connector_set;
- set.num_connectors = crtc_req->count_connectors;
+ set.num_connectors = num_connectors;
set.fb = fb;
if (drm_drv_uses_atomic_modeset(dev))
@@ -892,7 +893,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
drm_framebuffer_put(fb);
if (connector_set) {
- for (i = 0; i < crtc_req->count_connectors; i++) {
+ for (i = 0; i < num_connectors; i++) {
if (connector_set[i])
drm_connector_put(connector_set[i]);
}
