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mm: debug_page_alloc: fix NULL buf in debug_guardpage_minorder_setup To: Ye Liu , Andrew Morton , Vlastimil Babka Cc: Ye Liu , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260806004556.2633049-1-ye.liu@linux.dev> <0159349a-41f2-467c-b91a-3775e56a660f@nvidia.com> <6ae9914b-7254-4a1e-8345-597d3c2d7ea2@linux.dev> Content-Language: en-US From: John Hubbard In-Reply-To: <6ae9914b-7254-4a1e-8345-597d3c2d7ea2@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SJ0PR13CA0146.namprd13.prod.outlook.com (2603:10b6:a03:2c6::31) To DM3PR12MB9416.namprd12.prod.outlook.com (2603:10b6:0:4b::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM3PR12MB9416:EE_|SA0PR12MB4446:EE_ X-MS-Office365-Filtering-Correlation-Id: e5f6af9b-9c78-441f-dfad-08def3637cd6 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/5/26 6:56 PM, Ye Liu wrote: > > > 在 2026/8/6 09:08, John Hubbard 写道: >> On 8/5/26 5:45 PM, Ye Liu wrote: >>> From: Ye Liu >>> >>> If the kernel command line includes "debug_guardpage_minorder" without >>> an equals sign (i.e., no value is provided), the early parameter >>> parser passes a NULL buf pointer to the setup function. >>> >>> kstrtouint() does not perform a NULL check on its input and calls >>> directly into kstrtoull() which dereferences s[0] unconditionally, >>> leading to a NULL pointer dereference and early boot crash. >>> >>> Additionally, the error path's pr_err("%s", buf) would also crash with >>> a NULL format argument. >>> >> >> Maybe a "Fixes:" tag is called for? >> > > Add the following Fixes. Thanks. > > Fixes: c0a32fc5a2e4 ("mm: more intensive memory corruption debugging") > Looks good, Reviewed-by: John Hubbard thanks, -- John Hubbard >> >>> Signed-off-by: Ye Liu >>> --- >>> mm/debug_page_alloc.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c >>> index 41e3d1f1ad96..fd2664c3c86a 100644 >>> --- a/mm/debug_page_alloc.c >>> +++ b/mm/debug_page_alloc.c >>> @@ -22,8 +22,8 @@ static int __init debug_guardpage_minorder_setup(char *buf) >>> { >>> unsigned int res; >>> >>> - if (kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) { >>> - pr_err("Bad debug_guardpage_minorder value: %s\n", buf); >>> + if (!buf || kstrtouint(buf, 10, &res) < 0 || res > MAX_PAGE_ORDER / 2) { >>> + pr_err("Bad debug_guardpage_minorder value: %s\n", buf ?: "(missing)"); >>> return 0; >>> } >>> _debug_guardpage_minorder = res; >> >> thanks, >