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b=m2knUe1M/njq7jjIqMM0aYd0IQ1XadhqQ4jHEZXlizp3dwr2PJ2e3+wjZ0In7VD6r +/Pkf7DTaEef2gEGsEyTvnu1KWETnlSwseXzQ0BP6nB7fOkEZ0SwRdHibAG9V3aLz2 xFqh4wBNAyd/83J23xxCJTz6i06Xw7goDbYaJT8QMTkdJ5XPeVBWESgp3K0viBLkPs V30JcTeKkiT7nLtPEaHhjNVQGN/g9YjHKPZxpfJ4VxEiWx7GcEQQ8rtaegWUBuNW7l N+9jFDja10LrcQIoov0l7Vbv4xErtjZ11aJ7GMV9bJefR1ifZ3PmI3k7E5MWLp5cge wzrxfxhdONdbw== From: Pratyush Yadav To: Tarun Sahu Cc: Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Andrew Morton , Alexander Graf , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 1/3] mm/memfd_luo: validate serialized_data before conversion In-Reply-To: <20260623105201.3724592-2-tarunsahu@google.com> (Tarun Sahu's message of "Tue, 23 Jun 2026 10:51:59 +0000") References: <20260623105201.3724592-1-tarunsahu@google.com> <20260623105201.3724592-2-tarunsahu@google.com> Date: Tue, 23 Jun 2026 14:19:11 +0200 Message-ID: <2vxz5x39o3eo.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Stat-Signature: z6apo4hk8kik35ctq5hffstpr5s3zcqc X-Rspamd-Queue-Id: 88A68100012 X-Rspamd-Server: rspam06 X-HE-Tag: 1782217155-532837 X-HE-Meta: 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 wCx92YQO 4N7dOTLDMHs/Mm80XLu5KU2WC9AzO1j5KBvlznGlnqSzk1hQRyy/oNwtOgFkZvKuriN+qKZoZ1+OiTV9K9LB0o6o785+vCi2tDjKAMldiiv1ZFY2aTjXfZVILxGnCoM/ShoMAFdPNK6rcGF4ZOAdT8UdlmwMOF2NUtt7PAXZCCUwBTtNUHo+TMuX2RX3jjWq8Y8viJlnKAf+tShHHeq+uZGMk48sQXNwixH1WCPY/K8mx6VW+O/2+tXtdi+mVTs9rZcEM4oCsmAM4vuZZSm3xCIthfqub7G+8s/gVPi/6IdfCsPFf2aHi5emyaafWH7Ar8hgraH4x30LxLNw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 23 2026, Tarun Sahu wrote: > In memfd_luo_finish() and memfd_luo_retrieve(), phys_to_virt() was called > on args->serialized_data before checking if the physical address is valid. > Since physical address 0 does not map to virtual NULL (due to direct > mapping offsets), the subsequent check 'if (!ser)' was ineffective at > catching a missing serialized_data, leading to unsafe dereferences later. > > Validate that args->serialized_data is non-zero before calling > phys_to_virt(). > > Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") > Signed-off-by: Tarun Sahu Reviewed-by: Pratyush Yadav (Google) [...] -- Regards, Pratyush Yadav