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[2003:cb:c707:a100:e20:41da:c49b:8974]) by smtp.gmail.com with ESMTPSA id n18-20020adfe352000000b002c567881dbcsm12116359wrj.48.2023.03.07.02.04.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Mar 2023 02:04:38 -0800 (PST) Message-ID: <4c223e9c-2d43-fb8f-7ac9-ad2121914170@redhat.com> Date: Tue, 7 Mar 2023 11:04:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] mm: fix potential invalid pointer dereference in kmemdup() To: Xujun Leng , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230307090358.21346-1-lengxujun2007@126.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230307090358.21346-1-lengxujun2007@126.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 587DC16001C X-Stat-Signature: i8f3xch4pndgzc7r164gbqxi4s8m65z7 X-HE-Tag: 1678183482-56489 X-HE-Meta: U2FsdGVkX18XOdZaTF3n034TAivOecaoWylc4Ig0qyMvWi+mp+4a3jEl9x3l0FgPKqMOQl7N8JSWdnOePMQ3bP3P6Dk/NFTqM67X9I0jmtqmiHQ32ReUPjg2u13DAH8B6q+6fnRC8+SOx6yXVFBscZzkzkX1ySmftvLACSBVAThy7h58kS66cOKb0fGnWolANAHx3LGsPDjuPQm0qpRbGBdkLOnngKYbvVYB/zuMB39F71NauuqEPFKcoPNVvNshb26NZLDUUdQ0hdLzMRmofx06lL360bfnDMxk/w5f3ebt5+qHUSTJzTF0UY1a+ipVB5qGmzyfEQNmfwEhzyTD/hnSNsKkMFgzwacuLdecypAyPzq90ZtdB2niGbAFFLmOZjj/dNaqWbxjKKFHvOWqmasHZ+hDdtsiIdHxug+aOb4EFFT4EnmcxTFu/40EoRbftnfzd1QbMXAEA/30v34n+ZqtRrTjKD8gGvBp2fdqs15mxMqMFMYfP4I7BAc1FdZeygk9QGLjydTm1xFDSMmUePaFG/SAA/S9nRTjteYTgCFW4m7IcEj4mk2j4ovE80qvZuo8gOnJZfYXgfx3zoLeuX3voJaqhoImsuipANkmC9IByHfWAyGTEfJBfLCJ92GSgnMfN/1jE/MOPfKRnbCizmZ6PMLR3arqiRj4JKsP+Y82hGxQOhq9Z2c2+zgY2CEUg/uvJLqean505byKE90g089CWI8Q8pIuh5+EZiBFAV2JMgpM9sPTvWjlFfIggu8oYTMs4WthL4x73YEoz55AR9yJ+tck3QB5ZqoyL4v9apI+6YyzUoGyXeX7+GWmghtX72P2+7072NXLXS3Wwm//JOIXyEhBRfWcRxHlE0l7BRttX4gdn+EW4fZBXbsZ5XScvcNq2vzH4gh5mSlwPs2VLLKpRwQBBo36vNMs79pzwcfiaYhwjEMF2DwFFsYB1SEFISe8dI0dFv3C5wrK+6A /8otrNRR Bilww1owZwRIiuV2j0X7fVZjAYHrQ7zqffHS9ADZXbsRbdS57t4vIAF18FlpwxOHC16PYu+BlHYpx+pi8V+X6xoguIHA0x5HIh4dDyW1IgPe91Ljvd6mDHQG/dJz/0faeoXgZDkxvf61WTpTfRmho2TamhcXnpnUjnASSSvfaFAx3aImdzce/JzDBWnMesmPvTNd1J0Z3i5c7KzMlUMTmBiMnuBAAT/ZrfiYFMbhHFWLNuhCcnZ49iEONY/GqBi9b7GAuEBE/QsBDMfYjhcNqx4CoH1XMGs4LmiA5oh3p9AHhlpbNzc6V6dDVQcZOdunu/9VQtIIxwavtHPuq65o+gONYYnSlzDrncrbFnzZGLYMdgK9sFyevTTPHtXfSr5HOJrT4OBr0DvpqI3uPJ+/EI0uageKYpUOf6EAVIEwn5v/Hgpc= 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: On 07.03.23 10:03, Xujun Leng wrote: > If kmemdup() was called with src == NULL, then memcpy() source address > is fatal, and if kmemdup() was called with len == 0, kmalloc_track_caller() > will return ZERO_SIZE_PTR to variable p, then memcpy() destination address > is fatal. Both 2 cases will cause an invalid pointer dereference. > "fix" in subject implies that there is actually a case broken. Is there, or is this rather a "sanitize" ? > Signed-off-by: Xujun Leng > --- > mm/util.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/util.c b/mm/util.c > index dd12b9531ac4..d1a3b3d2988e 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -128,6 +128,9 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) > { > void *p; > > + if (!src || len == 0) > + return NULL; > + > p = kmalloc_track_caller(len, gfp); > if (p) > memcpy(p, src, len); Why should we take care of kmemdup(), but not memdup_user() ? Shouldn't it suffer from similar problems? -- Thanks, David / dhildenb