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List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Gui-Dong Han , linux-pm@vger.kernel.org, Georgi Djakov Cc: LKML , kernel-janitors@vger.kernel.org, Kuan-Wei Chiu , Wang Jiayue , Yao Zi References: <20260318024815.7655-1-hanguidong02@gmail.com> Subject: Re: [PATCH] interconnect: debugfs: fix devm_kstrdup and kfree mismatch Content-Language: en-GB, de-DE From: Markus Elfring In-Reply-To: <20260318024815.7655-1-hanguidong02@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:dKIqzHTSkvGCT0ns6nuZUAeCN6k/p5fReQUk3IYI3kwdq3LJWEk 3HxPR2J94qJJFv7bSpeNjDHdbQ8TUkDWOqHcql6KxuPsbDNLwsGgwZQT6hO/qD+crzNozik g0LlYhdnkML5L1XqaLiSwk2bhQjBpPWG2LCrpxTP482ZMEtx8MnHtOVmRYEZW790ChGHo+h AcwMjJQkmrsAGNVQdtMTw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:aWSsVJ/pi+k=;C7/nAL4AdCQemNKMEiAhSPi683e Jfq44XQhhD0spvN5Dyd7ptGP2HCtFsH+HSZHsrX07J2DqVv0tPUmmwbQOGPegj00JjSTKzRlS 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igT2Hnq/DMPV84+zhqdaCS5ILpYt1I+eG3J94WU5mOtilgPb0inHu6iJqrQ/hRYo8ny1K16+k zn3DJq6IpfgBDc/el+BEQwC4WKE5AemhW+ePhy2P/8eLMID032xnnwf5bxISxR0URNFgSVljx u3iuTjjQ1VkKDclgPevhBuFx1wXtrFABPBxjmmTSaHjqZph7JCdYMyc2soZ9zpf6iw6fjm+R3 Zr4hPfpG6HFVZea2Bburiue2mIQUIa8PKApNQTO0nX7idvW0ERJBIvTCNpkaNm4q90hXQRfZQ 3wQuVrW2lRJ6IsPupghBlEarw5QPo6UDJ3JelZEvHtsGExvFIdY2BbGCVvuBbPMuRdqDRPWOn xGY/XCg9DtnfpUQdYHzqTc/K3QYcqgAbXcnuGXTwZQtb+x2PZIW2FEZSmL2JeE9uOzTGoDYM7 Ih+7GdqllZaKW43dA6+iKTPGZw6NT//yLiFKT8fbrZ1ep6ntoSIp4A9XSy6XdN9zFMTm4MiGw hUyLPYVWX0p2NMTZbHcq > debugfs_write_file_str() uses standard kfree() to release old strings. Why would such information matter here? > Initializing src_node and dst_node with devm_kstrdup() creates a memory > management mismatch. If a user writes to these debugfs nodes, the > devm-allocated memory is freed via kfree(), leaving a dangling pointer > in the device resource list that can lead to a double free. Would an other description approach be clearer for involved dependencies? > Fix this by using standard kstrdup() instead. Interesting =E2=80=A6 https://elixir.bootlin.com/linux/v7.0-rc4/source/drivers/interconnect/debu= gfs-client.c#L139-L169 > Since the interconnect > subsystem is strictly built-in and cannot be unloaded as a module, there > is no exit path requiring manual cleanup of these strings. Should string lifetimes be reconsidered for the mentioned function impleme= ntation? > The error > handling path is also simplified by taking advantage of the fact that > kfree(NULL) is a safe no-op. I tend to interpret source code simplifications in other directions. See also once more: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Do= cumentation/process/stable-kernel-rules.rst?h=3Dv7.0-rc4#n34 Regards, Markus