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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by SJ1PEPF00002318.mail.protection.outlook.com (10.167.242.228) 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 17:13:50 +0000 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb07.amd.com (10.181.42.216) 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 12:13:47 -0500 Received: from [172.19.71.207] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.41 via Frontend Transport; Tue, 7 Jul 2026 12:13:46 -0500 Message-ID: Date: Tue, 7 Jul 2026 10:13:46 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH V1] accel/amdxdna: Fix potential amdxdna_umap lifetime race Content-Language: en-US To: Max Zhen , , , , , CC: , References: <20260706221228.434099-1-lizhi.hou@amd.com> <1b123fd9-12e5-4ca0-9328-97144af00f66@amd.com> From: Lizhi Hou In-Reply-To: <1b123fd9-12e5-4ca0-9328-97144af00f66@amd.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 9DE2gI22hrRUHfQY7d/2QcHaxEE75EYvncPNIQiygUtACKnzTU4pDOZ19/xBqWn2ALCLJ2igMrh6NrkTQH7vjsHV9Oy8VpXyWzcRZKvoAzEAb4KSNlim4Hhir3ls2lI0QLbl24b1F1fhiekgy1d6aM43TEca6FiZ/l/IsAag0JoVrbH+B3x+fvZm6sZe90tAg835MS5uCohxMd2TkzzsivHmO+ZrJhH/LG36X2oQo6CkWGXv+2OycjYF3B1D1D10ajB2PE2yhqcR89fZDXUevTgl4LrX6YqmOipCo1rA4vt0Y379e7VaHx4jKSidv6D7oOU6nUfuAlKu4LPgK7rhuiqDJ+qzaj1a0HtCgj9mhPcXeK+mHCjBKQojT6OZzJk3SuZ0iTfQAepIqq6mYK+xvSfviWK2X8vXgG3FGAnAXNQaEUfI0oupkQZXjxRh/Bh4 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2026 17:13:50.4233 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: db6755fb-44fb-4c75-3920-08dedc4b1d4d 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00002318.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS2PR12MB9663 Applied to drm-misc-fixes On 7/7/26 08:35, Max Zhen wrote: > > > 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; >