[kbuild] [ogabbay:habanalabs-next 17/19] drivers/misc/habanalabs/common/command_submission.c:2421 hl_cs_poll_fences() error: we previously assumed 'fence' could be null (see line 2402)

From: Dan Carpenter
Date: Mon Oct 11 2021 - 07:48:43 EST

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tree: https://git.kernel.org/pub/scm/linux/kernel/git/ogabbay/linux.git habanalabs-next
head: 41548e6097f0e2673e99c18aa74c9bbba341c9ba
commit: 2819e6243c5cdf6619cdaddaf117076a043d7bb2 [17/19] habanalabs: fix NULL pointer dereference
config: x86_64-randconfig-m001-20211011 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
drivers/misc/habanalabs/common/command_submission.c:2421 hl_cs_poll_fences() error: we previously assumed 'fence' could be null (see line 2402)

vim +/fence +2421 drivers/misc/habanalabs/common/command_submission.c

215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2346 static int hl_cs_poll_fences(struct multi_cs_data *mcs_data)
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2347 {
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2348 struct hl_fence **fence_ptr = mcs_data->fence_arr;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2349 struct hl_device *hdev = mcs_data->ctx->hdev;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2350 int i, rc, arr_len = mcs_data->arr_len;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2351 u64 *seq_arr = mcs_data->seq_arr;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2352 ktime_t max_ktime, first_cs_time;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2353 enum hl_cs_wait_status status;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2354
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2355 memset(fence_ptr, 0, arr_len * sizeof(*fence_ptr));
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2356
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2357 /* get all fences under the same lock */
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2358 rc = hl_ctx_get_fences(mcs_data->ctx, seq_arr, fence_ptr, arr_len);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2359 if (rc)
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2360 return rc;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2361
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2362 /*
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2363 * set to maximum time to verify timestamp is valid: if at the end
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2364 * this value is maintained- no timestamp was updated
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2365 */
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2366 max_ktime = ktime_set(KTIME_SEC_MAX, 0);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2367 first_cs_time = max_ktime;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2368
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2369 for (i = 0; i < arr_len; i++, fence_ptr++) {
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2370 struct hl_fence *fence = *fence_ptr;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2371
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2372 /*
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2373 * function won't sleep as it is called with timeout 0 (i.e.
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2374 * poll the fence)
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2375 */
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2376 rc = hl_wait_for_fence(mcs_data->ctx, seq_arr[i], fence,
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2377 &status, 0, NULL);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2378 if (rc) {
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2379 dev_err(hdev->dev,
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2380 "wait_for_fence error :%d for CS seq %llu\n",
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2381 rc, seq_arr[i]);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2382 break;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2383 }
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2384
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2385 /*
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2386 * It is possible to get an old sequence numbers from user
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2387 * which related to already completed CSs and their fences
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2388 * already gone. In this case, no need to consider its QID for
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2389 * mcs completion.
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2390 */
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2391 if (fence)
^^^^^
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2392 mcs_data->stream_master_qid_map |=
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2393 fence->stream_master_qid_map;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2394
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2395 /*
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2396 * Using mcs_handling_done to avoid possibility of mcs_data
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2397 * returns to user indicating CS completed before it finished
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2398 * all of its mcs handling, to avoid race the next time the
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2399 * user waits for mcs.
f0d5ad46a0eba1 drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-03 2400 */
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 2401 if (status == CS_WAIT_STATUS_BUSY ||
2819e6243c5cdf drivers/misc/habanalabs/common/command_submission.c Dani Liberman 2021-10-06 @2402 (fence && !fence->mcs_handling_done))
^^^^^
Checks for NULL

215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2403 continue;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2404
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2405 mcs_data->completion_bitmap |= BIT(i);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2406
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2407 /*
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2408 * best effort to extract timestamp. few notes:
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2409 * - if even single fence is gone we cannot extract timestamp
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2410 * (as fence not exist anymore)
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2411 * - for all completed CSs we take the earliest timestamp.
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2412 * for this we have to validate that:
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2413 * 1. given timestamp was indeed set
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2414 * 2. the timestamp is earliest of all timestamps so far
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2415 */
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2416
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2417 if (status == CS_WAIT_STATUS_GONE) {
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2418 mcs_data->update_ts = false;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2419 mcs_data->gone_cs = true;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2420 } else if (mcs_data->update_ts &&
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 @2421 (ktime_compare(fence->timestamp,
^^^^^^^
Unchecked dereferences.

215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2422 ktime_set(0, 0)) > 0) &&
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2423 (ktime_compare(fence->timestamp, first_cs_time) < 0)) {
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2424 first_cs_time = fence->timestamp;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2425 }
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2426 }
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2427
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2428 hl_fences_put(mcs_data->fence_arr, arr_len);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2429
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2430 if (mcs_data->update_ts &&
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2431 (ktime_compare(first_cs_time, max_ktime) != 0))
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2432 mcs_data->timestamp = ktime_to_ns(first_cs_time);
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2433
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2434 return rc;
215f0c1775d550 drivers/misc/habanalabs/common/command_submission.c Ohad Sharabi 2021-06-14 2435 }

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