linux-kernel - [PATCH v2] drm/xe/hw_engine_group: Fix bad free in xe_hw_engine_setup

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Message-Id: <20241115024941.3737042-1-suhui@nfschina.com>
Date: Fri, 15 Nov 2024 10:49:42 +0800
From: Su Hui <suhui@...china.com>
To: balasubramani.vivekanandan@...el.com,
	lucas.demarchi@...el.com,
	thomas.hellstrom@...ux.intel.com,
	rodrigo.vivi@...el.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	nathan@...nel.org,
	ndesaulniers@...gle.com,
	morbo@...gle.com,
	justinstitt@...gle.com
Cc: Su Hui <suhui@...china.com>,
	matthew.brost@...el.com,
	francois.dugast@...el.com,
	intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev,
	kernel-janitors@...r.kernel.org
Subject: [PATCH v2] drm/xe/hw_engine_group: Fix bad free in xe_hw_engine_setup_groups()

Clang static checker(scan-build) warning：
drivers/gpu/drm/xe/xe_hw_engine_group.c: line 134, column 2
Argument to kfree() is a constant address (18446744073709551604), which
is not memory allocated by malloc().

kfree() can only handle NULL pointers instead of negitave error codes.
When hw_engine_group_alloc() failed, there is a bad kfree call for
negitave error codes in xe_hw_engine_setup_groups().

Free 'group' when alloc_workqueue() failed in hw_engine_group_alloc(), and
remove wrong kfree() in xe_hw_engine_setup_groups() to fix this problem.
It's safe to remove these kfree() because drmm_add_action_or_reset()
can free these by calling hw_engine_group_free().

Fixes: d16ef1a18e39 ("drm/xe/exec: Switch hw engine group execution mode upon job submission")
Fixes: f784750c670f ("drm/xe/hw_engine_group: Introduce xe_hw_engine_group")
Signed-off-by: Su Hui <suhui@...china.com>
---
v2:
 - remove wrong destroy_workqueue() and kfree() in v1 patch
v1:
 - https://lore.kernel.org/all/20241114063942.3448607-1-suhui@nfschina.com/

 drivers/gpu/drm/xe/xe_hw_engine_group.c | 32 +++++++------------------
 1 file changed, 9 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_hw_engine_group.c b/drivers/gpu/drm/xe/xe_hw_engine_group.c
index 82750520a90a..3bfa002734ad 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine_group.c
+++ b/drivers/gpu/drm/xe/xe_hw_engine_group.c
@@ -58,8 +58,10 @@ hw_engine_group_alloc(struct xe_device *xe)
 		return ERR_PTR(-ENOMEM);
 
 	group->resume_wq = alloc_workqueue("xe-resume-lr-jobs-wq", 0, 0);
-	if (!group->resume_wq)
+	if (!group->resume_wq) {
+		kfree(group);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	init_rwsem(&group->mode_sem);
 	INIT_WORK(&group->resume_work, hw_engine_group_resume_lr_jobs_func);
@@ -84,25 +86,18 @@ int xe_hw_engine_setup_groups(struct xe_gt *gt)
 	enum xe_hw_engine_id id;
 	struct xe_hw_engine_group *group_rcs_ccs, *group_bcs, *group_vcs_vecs;
 	struct xe_device *xe = gt_to_xe(gt);
-	int err;
 
 	group_rcs_ccs = hw_engine_group_alloc(xe);
-	if (IS_ERR(group_rcs_ccs)) {
-		err = PTR_ERR(group_rcs_ccs);
-		goto err_group_rcs_ccs;
-	}
+	if (IS_ERR(group_rcs_ccs))
+		return PTR_ERR(group_rcs_ccs);
 
 	group_bcs = hw_engine_group_alloc(xe);
-	if (IS_ERR(group_bcs)) {
-		err = PTR_ERR(group_bcs);
-		goto err_group_bcs;
-	}
+	if (IS_ERR(group_bcs))
+		return PTR_ERR(group_bcs);
 
 	group_vcs_vecs = hw_engine_group_alloc(xe);
-	if (IS_ERR(group_vcs_vecs)) {
-		err = PTR_ERR(group_vcs_vecs);
-		goto err_group_vcs_vecs;
-	}
+	if (IS_ERR(group_vcs_vecs))
+		return PTR_ERR(group_vcs_vecs);
 
 	for_each_hw_engine(hwe, gt, id) {
 		switch (hwe->class) {
@@ -125,15 +120,6 @@ int xe_hw_engine_setup_groups(struct xe_gt *gt)
 	}
 
 	return 0;
-
-err_group_vcs_vecs:
-	kfree(group_vcs_vecs);
-err_group_bcs:
-	kfree(group_bcs);
-err_group_rcs_ccs:
-	kfree(group_rcs_ccs);
-
-	return err;
 }
 
 /**
-- 
2.30.2