[PATCH] drm/amdkfd: rework criu_restore_bos error handling

[trix at redhat.com]

From: Tom Rix <trix at redhat.com>

Clang static analysis reports this problem
kfd_chardev.c:2327:2: warning: 1st function call argument
  is an uninitialized value
  kvfree(bo_privs);
  ^~~~~~~~~~~~~~~~

If the copy_from_users(bo_buckets, ...) fails, there is a jump to
the generic error handler at exit:.  The freeing of bo_privs and
unwinding of the dmabuf_fd loop do not need to be done.

Add some specific labels for the early failures.
Reorder the frees to be the reverse of their allocs.

Move the initialize of 'i' back to the loop.
The problem with the early frees predates the loop
unwinding problem.

Fixes: 73fa13b6a511 ("drm/amdkfd: CRIU Implement KFD restore ioctl")
Signed-off-by: Tom Rix <trix at redhat.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 965af2a08bc0..1d5f41ac3832 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -2102,7 +2102,7 @@ static int criu_restore_bos(struct kfd_process *p,
 	const bool criu_resume = true;
 	bool flush_tlbs = false;
 	int ret = 0, j = 0;
-	uint32_t i = 0;
+	uint32_t i;
 
 	if (*priv_offset + (args->num_bos * sizeof(*bo_privs)) > max_priv_data_size)
 		return -EINVAL;
@@ -2119,13 +2119,13 @@ static int criu_restore_bos(struct kfd_process *p,
 	if (ret) {
 		pr_err("Failed to copy BOs information from user\n");
 		ret = -EFAULT;
-		goto exit;
+		goto free_buckets;
 	}
 
 	bo_privs = kvmalloc_array(args->num_bos, sizeof(*bo_privs), GFP_KERNEL);
 	if (!bo_privs) {
 		ret = -ENOMEM;
-		goto exit;
+		goto free_buckets;
 	}
 
 	ret = copy_from_user(bo_privs, (void __user *)args->priv_data + *priv_offset,
@@ -2133,12 +2133,12 @@ static int criu_restore_bos(struct kfd_process *p,
 	if (ret) {
 		pr_err("Failed to copy BOs information from user\n");
 		ret = -EFAULT;
-		goto exit;
+		goto free_privs;
 	}
 	*priv_offset += args->num_bos * sizeof(*bo_privs);
 
 	/* Create and map new BOs */
-	for (; i < args->num_bos; i++) {
+	for (i = 0; i < args->num_bos; i++) {
 		struct kfd_criu_bo_bucket *bo_bucket;
 		struct kfd_criu_bo_priv_data *bo_priv;
 		struct kfd_dev *dev;
@@ -2323,8 +2323,11 @@ static int criu_restore_bos(struct kfd_process *p,
 		if (bo_buckets[i].alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_VRAM)
 			close_fd(bo_buckets[i].dmabuf_fd);
 	}
-	kvfree(bo_buckets);
+free_privs:
 	kvfree(bo_privs);
+free_buckets:
+	kvfree(bo_buckets);
+
 	return ret;
 }
 
-- 
2.26.3