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client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by SJ1PEPF00001CDF.mail.protection.outlook.com (10.167.242.7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.181.6 via Frontend Transport; Tue, 7 Jul 2026 15:35:47 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Tue, 7 Jul 2026 10:35:46 -0500 Received: from [172.19.70.117] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.41 via Frontend Transport; Tue, 7 Jul 2026 10:35:46 -0500 Message-ID: <1b123fd9-12e5-4ca0-9328-97144af00f66@amd.com> Date: Tue, 7 Jul 2026 08:35:45 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V1] accel/amdxdna: Fix potential amdxdna_umap lifetime race To: Lizhi Hou , , , , , CC: , References: <20260706221228.434099-1-lizhi.hou@amd.com> Content-Language: en-US From: Max Zhen In-Reply-To: <20260706221228.434099-1-lizhi.hou@amd.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: HnDqPPgsA0UKiZnPovel4MVm+XIZZU9zpBzBPKzioOX7EI6iawTg5zdf0peeh0B+Ul5abpq0n2OZ6TnYnOaa3/+C1s+CHj7ZUnhSHhKJLIzxcUOl9AVrTzohALBqhF1wFjTwzZ6vP+wPIhOS7O1xBtC9i1HG7aVg5xzdyjPVl89KCyYDukdDNnmk3qV0vzALsxm0+VIh5skyvkUu+S8kSZ6cgzrkANDtwea9GHuOWvopD9nNPTUQNAqdXjK3LJDHeTGL+ljOLs9HI21m4mEwFb4M4dKcConfMitWEo6DM4fHLXpY0RlB9q5FpKNZBIofeodYavyVYLb9JF8s0fZFFfbD6AZ9IYqDeCETWmednkfBUFN9zAynJgBNnwFUcPTkkIW/FumvPTnRyMjCclsXQClHYqBFLTax1qWFe75tpairwIdVjH/BpLeMLdCwYkfw X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2026 15:35:47.0042 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 28d0473a-4071-446a-d887-08dedc3d6a7e X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00001CDF.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4351 On 7/6/2026 Mon 15:12, Lizhi Hou wrote: > amdxdna_umap_release() calls the blocking mmu_interval_notifier_remove() > before removing the object from abo->mem.umap_list. If > aie2_populate_range() runs concurrently, it may obtain a reference to an > amdxdna_umap that is being released, leading to a potential use-after-free. > > Use refcount_inc_not_zero() in aie2_populate_range() when acquiring a > reference. If the reference count has already dropped to zero, release > is in progress and the entry is skipped. > > Fixes: e486147c912f ("accel/amdxdna: Add BO import and export") > Signed-off-by: Lizhi Hou Reviewed-by: Max Zhen The patch description mentioned refcount_inc_not_zero(), but the real fix calls kref_get_unless_zero() which is a wrapper of refcount_inc_not_zero(). It might be better to fix the description to match the fix in the code. Thanks, Max > --- > drivers/accel/amdxdna/aie2_ctx.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/accel/amdxdna/aie2_ctx.c b/drivers/accel/amdxdna/aie2_ctx.c > index 408ff7e2a272..7bf635634e64 100644 > --- a/drivers/accel/amdxdna/aie2_ctx.c > +++ b/drivers/accel/amdxdna/aie2_ctx.c > @@ -1039,7 +1039,7 @@ static int aie2_populate_range(struct amdxdna_gem_obj *abo) > found = false; > down_write(&xdna->notifier_lock); > list_for_each_entry(mapp, &abo->mem.umap_list, node) { > - if (mapp->invalid) { > + if (mapp->invalid && kref_get_unless_zero(&mapp->refcnt)) { > found = true; > break; > } > @@ -1050,7 +1050,7 @@ static int aie2_populate_range(struct amdxdna_gem_obj *abo) > up_write(&xdna->notifier_lock); > return 0; > } > - kref_get(&mapp->refcnt); > + > up_write(&xdna->notifier_lock); > > mm = mapp->notifier.mm;