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imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=SCCDxpSv; spf=pass (imf05.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787247079; b=NIy/fwgrcRI+MfRA/ZU2BnyHhzl2MIge2kCuxin97xLHnWzB56TU0m3m3eJwoORHuup9LE 3Ng1h/+bQs+39UMrXIJlMdsJfbCU7GghbHj76f7oO63DgRw4N8PqmhOSAzo/Mevb9SN6Jx ghvb++9cxRpJ7maGugiWNLVCdNvjKl0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C857240F01; Thu, 20 Aug 2026 17:31:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 022931F000E9; Thu, 20 Aug 2026 17:31:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787247078; bh=RjicE+rPS3y28uBHFm/mdXNkgiy6AiD+cc8tWN9zzKQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=SCCDxpSvivp23EzOE1anqeLvcDunLreP1GHlzp1LfpFY+GcLHQmNpuDuVwiuxswyg 6pU/mDROTUz3lyhhgfJyfthTtE/Jdk00OjuHXtLkxWXefgqyCCYhw/katvP8i5AqSg +vUeExiROM0WniQYhy0kPjBFH4gikpfeIrvf5rJT3PiTRfMe9k8LoW29bKjX1LqsWT kTkoSnnWqiilN7zLfLSi8+28SIR70ZlE0FKP+d3z0IjNSTtPD7eIdF1/i/HuN2I09P 7/5/1pRM7t8Roe4qLV7UZ7HgMovkF7U4BvSEO53aWBRtTZwOCfNcCJNyH8GpBY7wNC lFYbJ229M54BA== Message-ID: <00fad295-132f-49ea-9a39-0febf0919ad5@kernel.org> Date: Thu, 20 Aug 2026 19:31:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: check stat() return value in khugepaged get_finfo() To: Anshuman , Andrew Morton , Lorenzo Stoakes Cc: Shuah Khan , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260819121426.49500-1-anshumantewari123@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260819121426.49500-1-anshumantewari123@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CDB51100007 X-Stat-Signature: myytfaapnfgswwh635hizk76hknhoee7 X-Rspam-User: X-HE-Tag: 1787247079-86687 X-HE-Meta: U2FsdGVkX1+cC72TDnLUieqQloLBTo8eD6SF6DZ6/ezboTSlffHCwNZ3iPzmVie0CNMwhS118abH4wnMYhXarrifFAE0teWMuQF/AmYhItq4VUxftMO7C+/FKECks0QmN4lO1gD1DM9imSbiA4KSA3gS/mkr8SMWQQSlLrHPoHs2dqg9vPiTNj25SWUefopdQZQKHIq8KQ35zInsGHD6D1JrHe5i/jvlKxhNNOWzqGWzOfkjB2/XNmtCZXq74q+eITXJuM2nALb41lhBONqiX9n4FofplNO014RyB0/Bf5K3RXFPNwfulP0YFFziorTI4YEBw9I3zWY8iZk+8ACRy/BsKvofGawTPd1embhUo/VXDsEu7ZQFdErsrpSJoW9PYjWEn8fLKnleTSUquUQRc9O9nzDzTq6qGj4T4KVltBIeCKoU+LJpVHWXsLBuJtRLuZBa/DrBsQ614E+Ox3tgY2qT5vGh2NeSBTzY/s3Y6keaYvMSu13dk7wTPGzUzdec9q1LBQXZRef+SgQg1j16KrKcXQiUYWZJYIIP8VIJcj95jtSBZmr7yKEun1u1ELE5GE0TXD8lsQ3ltDArB9JDhpjhRCdy+lzUK10og8YBXOzG2fV2NnQG7623ABUIMTHHbRIlsTLD2r6Ek0KOcPGpOYTxNf9KhleXwLhRJHHfsw2Mz72id0YeuxIpGFOCXeXyE+xNDaVe+V1TOdXTF4CKTsCsHnepdRd4SIhZxVjfNBPdKXZ4S9brFJOdiQOLmjAILSNIcgknHGoKiBevrf1hV21YgVrv1TYbD3Sn3xGsPGZjY53SRfQ0zTZXjbfNXIm9/6VOnhm9JVIia3hENLJyq/cFW00drYjLAkmiHc8bC61Lzou5F/C0oVOHsDJ5WCuN9Z3JVMh04X9DsT/dzLubRXM7g89y3rBPmH3Xv0AxW/AwNQBVW8f9oY3HD9C5Ui+NTEw8X9NWqJEwSPHRg7Y ZowEY1L9 7nq6K/UVg5jhmjRZyydqsQxr+ef7XTk5qI+FnuG11m1QLGPadcEZSgQDYilLLfsh37TC8HGuHLcL8Yx5o6m3sEBfev75v2yJsX7E+yimshBGZu7m5ooiJBojiU8YE0i5ulnXZkaMSv2Va65uvaB/EapCD/IryYViVx1Pj/DfIvMcMf42yOATdUwO2ALj4uuZYgRuv8ALnmDfNFI7BSQlf3btDkqc5boBgrLjd1srzHAYNnn+bW0GSDnp7mg6BRasXdCkdzzt69Ss/OIol+YAJlq6a3qPnmUkuDpUit31Q828vyBMYMB2KeuIYLTlkfYiA5ZEe5JWUtFlYNdjUN0ozcqGkkIqR2k8YhHx+ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/19/26 14:14, Anshuman wrote: > get_finfo() calls stat() to get metadata about the target directory, > but never checks the return value. On failure, stat() returns -1 and > leaves path_stat unmodified, so path_stat.st_mode may contain > uninitialized stack data. > > The code then checks S_ISDIR(path_stat.st_mode) against this > potentially garbage value. This can produce a misleading "Not a > directory" error when the real problem is a nonexistent or > inaccessible path, or, in the worst case, the check could pass by > chance on garbage data and let the function continue using an > invalid path_stat for the rest of its logic. > > Check the return value and fail with a clear error message if > stat() fails, matching the error-handling style already used for > statfs() and read_file() later in the same function. > > Signed-off-by: Anshuman > --- > tools/testing/selftests/mm/khugepaged.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c > index 10e8dedcb..2240a9b4f 100644 > --- a/tools/testing/selftests/mm/khugepaged.c > +++ b/tools/testing/selftests/mm/khugepaged.c > @@ -121,7 +121,8 @@ static void get_finfo(const char *dir) > char *str, *end; > > finfo.dir = dir; > - stat(finfo.dir, &path_stat); > + if (stat(finfo.dir, &path_stat)) > + ksft_exit_fail_perror("stat()"); > if (!S_ISDIR(path_stat.st_mode)) > ksft_exit_fail_msg("%s: Not a directory (%s)\n", __func__, finfo.dir); > if (snprintf(finfo.path, sizeof(finfo.path), "%s/" TEST_FILE, >From out selftests that should mostly be impossible to trigger, as run_vmtests.sh will just create that directory. So it's a valid improvement, but mostly irrelevant in practice 1Acked-by: David Hildenbrand (Arm) -- Cheers, David