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Tyllis Xu
fe31722b01
commit9aad71144fupstream. The ibmasm_send_i2o_message() function uses get_dot_command_size() to compute the byte count for memcpy_toio(), but this value is derived from user-controlled fields in the dot_command_header (command_size: u8, data_size: u16) and is never validated against the actual allocation size. A root user can write a small buffer with inflated header fields, causing memcpy_toio() to read up to ~65 KB past the end of the allocation into adjacent kernel heap, which is then forwarded to the service processor over MMIO. Silently clamping the copy size is not sufficient: if the header fields claim a larger size than the buffer, the SP receives a dot command whose own header is inconsistent with the I2O message length, which can cause the SP to desynchronize. Reject such commands outright by returning failure. Validate command_size before calling get_mfa_inbound() to avoid leaking an I2O message frame: reading INBOUND_QUEUE_PORT dequeues a hardware frame from the controller's free pool, and returning without a corresponding set_mfa_inbound() call would permanently exhaust it. Additionally, clamp command_size to I2O_COMMAND_SIZE before the memcpy_toio() so the MMIO write stays within the I2O message frame, consistent with the clamping already performed by outgoing_message_size() for the header field. Fixes:1da177e4c3("Linux-2.6.12-rc2") Reported-by: Yuhao Jiang <danisjiang@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Tyllis Xu <LivelyCarpet87@gmail.com> Link: https://patch.msgid.link/20260314165805.548293-1-LivelyCarpet87@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>