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Sat, 8 Feb 2025 09:37:29 +0800 (CST) Received: from huawei.com (10.67.174.33) by kwepemg100016.china.huawei.com (7.202.181.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 8 Feb 2025 09:37:29 +0800 From: GONG Ruiqi To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Kees Cook CC: Tamas Koczka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Xiu Jianfeng , , , , Subject: [PATCH v2 2/2] slab: Achieve better kmalloc caches randomization in kvmalloc Date: Sat, 8 Feb 2025 09:47:23 +0800 Message-ID: <20250208014723.1514049-3-gongruiqi1@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250208014723.1514049-1-gongruiqi1@huawei.com> References: <20250208014723.1514049-1-gongruiqi1@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.33] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemg100016.china.huawei.com (7.202.181.57) X-Rspam-User: X-Rspamd-Queue-Id: 3DF09120008 X-Rspamd-Server: rspam12 X-Stat-Signature: 3nshzmunb86iep9qq9gki6jbjga1skmo X-HE-Tag: 1738978652-41009 X-HE-Meta: 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 tgil3IRN RuTUzGqNH8Zf/Jnu+i96DFy7uKNIu8Dz5gE62XNGBpJlXzPuYjuIA2cW6WKdq+ra8gFuVPPA7qRHXN00iBQBIDhj4c4n/01NhsEQdmzOYbdcTGYO8g4fRVQqAFPclyj8kXS2sMioUDCtGn9xveKxBNkS8/GH/fL8Jv2Z0JXaUfjVuM8htag5+6dtuvlK2G+GIzbFAOxu5Zwe1Wros1WGzfwvlr2mkL+/TmtgD6Drgk9JlY9MO3T5T69G+ABBC/vJCiaTCIqMmFGKNVubK4y02GIFUVQklC/YbHvAZEHTZOTi03zk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: As revealed by this writeup[1], due to the fact that __kmalloc_node (now renamed to __kmalloc_node_noprof) is an exported symbol and will never get inlined, using it in kvmalloc_node (now is __kvmalloc_node_noprof) would make the RET_IP inside always point to the same address: upper_caller kvmalloc kvmalloc_node kvmalloc_node_noprof __kvmalloc_node_noprof <-- all macros all the way down here __kmalloc_node_noprof __do_kmalloc_node(.., _RET_IP_) ... <-- _RET_IP_ points to That literally means all kmalloc invoked via kvmalloc would use the same seed for cache randomization (CONFIG_RANDOM_KMALLOC_CACHES), which makes this hardening unfunctional. The root cause of this problem, IMHO, is that using RET_IP only cannot identify the actual allocation site in case of kmalloc being called inside wrappers or helper functions. And I believe there could be similar cases in other functions. Nevertheless, I haven't thought of any good solution for this. So for now let's solve this specific case first. For __kvmalloc_node_noprof, replace __kmalloc_node_noprof and call __do_kmalloc_node directly instead, so that RET_IP can take the return address of kvmalloc and differentiate each kvmalloc invocation: upper_caller kvmalloc kvmalloc_node kvmalloc_node_noprof __kvmalloc_node_noprof <-- all macros all the way down here __do_kmalloc_node(.., _RET_IP_) ... <-- _RET_IP_ points to Thanks to Tamás Koczka for the report and discussion! Link: https://github.com/google/security-research/pull/83/files#diff-1604319b55a48c39a210ee52034ed7ff5b9cdc3d704d2d9e34eb230d19fae235R200 [1] Reported-by: Tamás Koczka Signed-off-by: GONG Ruiqi --- mm/slub.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 0830894bb92c..46e884b77dca 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4903,9 +4903,9 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node) * It doesn't really make sense to fallback to vmalloc for sub page * requests */ - ret = __kmalloc_node_noprof(PASS_BUCKET_PARAMS(size, b), - kmalloc_gfp_adjust(flags, size), - node); + ret = __do_kmalloc_node(size, PASS_BUCKET_PARAM(b), + kmalloc_gfp_adjust(flags, size), + node, _RET_IP_); if (ret || size <= PAGE_SIZE) return ret;