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b=ePztP8aQhD2iLU3urqNcWGSwX3LpkF6rDc5L4zwTynmBf8maf3O1jDhc9T2Hl6aCQ wJeqvdwRwOGR1nRwV5rCfkNQUnOeheZh/5zLWxpMKjDuM8IcRl6sQdY30vmH3jJJaq 2tNn3QQoBPdmZdBsrngGJQnz+4XGzEZZzRV9Q3oKpd4qY7DivuReOLF5iYF4ML3aJI e1ZzDmsZ9ywQ1rvhNd5bTcWFLky8KneWSf3DS/2r2C5i46O6n1/hHV9cmT4wqQ6F8f /ENsCgKF8rVTRl2lJEFm3wKeDFZI9hZKV4vbY3U3TaUWYbcwM/wQjtE3ZjeAK/Bj2T HOE619OPLA9Uw== From: Pratyush Yadav To: Tarun Sahu Cc: Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Andrew Morton , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/memfd_luo: validate serialized_data before conversion In-Reply-To: (Tarun Sahu's message of "Thu, 11 Jun 2026 10:30:03 +0000") References: Date: Thu, 11 Jun 2026 14:32:51 +0200 Message-ID: <2vxzv7bpqmto.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: DF6A21A0009 X-Stat-Signature: f71awnwu9sgzjg1376rsx3nappuoexa8 X-Rspam-User: X-HE-Tag: 1781181174-348236 X-HE-Meta: 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 UVdMXkE8 dnUQZ3AlBFHmobbWtRo5Hy59ywa8NMriBih0fXiFaXreW5HxzD5c+w4Sm7eVHNXy3B7Xfntb3t05fhYWYVLRIrdxnZgApEZyPuP+4IbF14VbBGckFsY0Q8Y+bqp2zvM5mvXeqBsSwf6THigeXy1KW7bKD3a7MHBlnZTEbfbKkbDBs4VyWmHy2YazV/Ghqi/hJpg8MiafrnF3XXEU3xA8sGMtZPdk3MXKdjQ9uH1ZZ2gRMZZY+0QtG+i5HDAv0jKCspWsM2Ed+j9LUlajhzoneanm/ViDj60RJOPy8PA1CLD74YJG/igZMHs5HporgXl0abi9yLO45P0vvVMM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 11 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 Nit: this is only true on ARM64. On x86 physical address of 0 maps to NULL. Other than this, Reviewed-by: Pratyush Yadav (Google) > 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 [...] -- Regards, Pratyush Yadav