From: Oded Gabbay <ogabbay@kernel.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: kbuild@lists.01.org, Dani Liberman <dliberman@habana.ai>,
kbuild test robot <lkp@intel.com>,
kbuild-all@lists.01.org,
"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>
Subject: Re: [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)
Date: Mon, 11 Oct 2021 16:59:09 +0300 [thread overview]
Message-ID: <CAFCwf10o1gGqxztuKy9jVeed9FCjE=iE_mCu5AeD6iOWiNFt_A@mail.gmail.com> (raw)
In-Reply-To: <202110111947.2oUxucXl-lkp@intel.com>
On Mon, Oct 11, 2021 at 2:48 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> 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@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> 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.
Hi Dan,
Thanks for the report.
I believe this is a false positive, because if the fence is NULL, then
status *must* be CS_WAIT_STATUS_GONE.
I agree the code is not well written here and you can only understand
the above if you go and look in
the code of hl_wait_for_fence().
Therefore, we will refactor the code here to make it more readable and
depend only on the status field
instead of checking if the fence pointer is NULL.
Oded
>
> 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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> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>
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prev parent reply other threads:[~2021-10-11 14:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 11:48 [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) Dan Carpenter
2021-10-11 13:59 ` Oded Gabbay [this message]
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