[PATCH 6.6 074/150] drm/crtc: Fix uninit-value bug in drm_mode_setcrtc

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



6.6-stable review patch.  If anyone has any objections, please let me know.

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

From: Ziqi Zhao <astrajoan@xxxxxxxxx>

[ 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>
---
 drivers/gpu/drm/drm_crtc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

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]);
 		}
-- 
2.43.0







[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux