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[24.205.208.113]) by smtp.gmail.com with ESMTPSA id f14sm23160886qko.117.2022.02.18.18.34.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Feb 2022 18:34:44 -0800 (PST) Subject: Re: [PATCH] drm/amdkfd: rework criu_restore_bos error handling To: Felix Kuehling , alexander.deucher@amd.com, christian.koenig@amd.com, Xinhui.Pan@amd.com, airlied@linux.ie, daniel@ffwll.ch, nathan@kernel.org, ndesaulniers@google.com, david.yatsin@amd.com, rajneesh.bhardwaj@amd.com Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20220218173913.3376948-1-trix@redhat.com> From: Tom Rix Message-ID: <4ca24c08-9014-3380-b8cc-dc0ed9a01a73@redhat.com> Date: Fri, 18 Feb 2022 18:34:41 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=trix@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US On 2/18/22 10:35 AM, Felix Kuehling wrote: > Am 2022-02-18 um 12:39 schrieb trix@redhat.com: >> From: Tom Rix >> >> 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. > > I think the existing error handling strategy in this function is fine. > Having only one exit label avoids potential issues when using the > wrong label. Freeing NULL pointers is not a problem. The loop becomes > a noop if i==0 (this was fixed by you in a previous patch). The only > real problem I see is that bo_privs is not initialized. So this should > really be a one-line or maybe two-line fix: > >     struct kfd_criu_bo_bucket *bo_buckets = NULL; >     struct kfd_criu_bo_priv_data *bo_privs = NULL; This is the other way I considered to fix the problem. So it will work. Tom > > Regards, >   Felix > > >> >> Fixes: 73fa13b6a511 ("drm/amdkfd: CRIU Implement KFD restore ioctl") >> Signed-off-by: Tom Rix >> --- >>   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; >>   } >