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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260817-limit_kmalloc_size-v1-1-5bef487701cc@nvidia.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yXMTQ6CQAxA4auQrp0EZowYrkIMKaVoZfjJFIyRc HcGWX6L91ZQDsIKRbJC4I+ojENEdkmAXjg82UgTDTa1t/Se5cZLL3PV9ej9SJXKj43DK1rKXc1 IEMMpcCvf/7R8nNalfjPNxwm2bQe9w/MCdgAAAA== X-Change-ID: 20260817-limit_kmalloc_size-3a4a2c73beac To: Vlastimil Babka , Harry Yoo , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Alan Stern , Greg Kroah-Hartman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzbot+805630f1453e490427fa@syzkaller.appspotmail.com, Zi Yan , stable@vger.kernel.org X-Mailer: b4 0.15.2 X-ClientProxiedBy: YQZPR01CA0167.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:8c::23) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|MN6PR12MB8591:EE_ X-MS-Office365-Filtering-Correlation-Id: ebdac203-6960-4f46-830f-08defc9fc7fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|23010399003|7416014|376014|366016|6133799003|10067099003|11063799006|56012099006|18002099003; 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For requests larger than KMALLOC_MAX_CACHE_SIZE, kmalloc uses the page allocator and can only support up to KMALLOC_MAX_SIZE. For request sizes bigger than KMALLOC_MAX_SIZE, the page allocator can emit a WARN because kmalloc allocates an order greater than MAX_PAGE_ORDER. Systems with panic_on_warn=1 crash because of this WARN. Fix it by rejecting any kmalloc size bigger than KMALLOC_MAX_SIZE. Fixes: aadb4bc4a1f9 ("SLUB: direct pass through of page size or higher kmalloc requests") Reported-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6a820ebc.9ebadd4d.20b15e.001b.GAE@google.com/ Tested-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com Signed-off-by: Zi Yan Cc: stable@vger.kernel.org --- It fixes a page allocator warning (order > MAX_PAGE_ORDER) when gadgetfs requests excessively large memory from kmalloc. Instead of adding __GFP_NOWARN to suppress the warning, as was done for usbfs[1], change kmalloc to return NULL without a warning for this specific issue. [1] commit 4f2629ea67e72 ("USB: usbfs: Don't WARN about excessively large memory allocations") --- mm/slub.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 0337e60db5ace..a3071f4ef1945 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5263,7 +5263,12 @@ static void *___kmalloc_large_node(size_t size, gfp_t flags, int node) { struct page *page; void *ptr = NULL; - unsigned int order = get_order(size); + unsigned int order; + + if (size > KMALLOC_MAX_SIZE) + return NULL; + + order = get_order(size); if (unlikely(flags & GFP_SLAB_BUG_MASK)) flags = kmalloc_fix_flags(flags); --- base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f change-id: 20260817-limit_kmalloc_size-3a4a2c73beac Best regards, -- Yan, Zi