The NXP GAU ADC driver (drivers\/adc\/adc_mcux_gau_adc.c) validated the caller-supplied sequence->buffer_size, which is expressed in bytes, against the number of active channels, which is a sample count. It then stored that byte count directly in data->results_length and used it in mcux_gau_adc_read_samples() as the number of uint16_t slots available. Because each conversion result occupies sizeof(uint16_t) bytes, a buffer that was accepted as “large enough” could be written with up to twice its size in bytes, so every sample past the buffer’s midpoint was written out of bounds.<\/p>\n
adc_read() and adc_read_async() are Zephyr system calls. The syscall verifier in drivers\/adc\/adc_handlers.c only confirms that the caller owns buffer_size writable bytes (K_SYSCALL_MEMORY_WRITE); deciding whether that size is sufficient for the requested channels and extra_samplings is delegated entirely to the driver. On a build with CONFIG_USERSPACE=y, a user-mode thread that has been granted the ADC device object could therefore submit a deliberately half-sized buffer and cause the driver’s work-queue handler \u2014 which runs in supervisor mode, outside the caller’s MPU restrictions \u2014 to write ADC conversion results past the end of that buffer, at an address and for a length of the caller’s choosing.<\/p>\n
The overrun is bounded by the requested sequence: with sequence->options->extra_samplings set, the sampling loop walks the buffer pointer forward across every sampling, so the total overrun can reach the full size of the supplied buffer (kilobytes for a large extra_samplings). The written words are 16-bit ADC conversion results, so the content is only partially attacker-influenced (via the selected analog input, gain and resolution), but the destination and length are fully controlled \u2014 sufficient for kernel memory corruption, a crash, or a userspace-to-kernel privilege escalation. Builds without CONFIG_USERSPACE, or on SoCs other than NXP RW61x with the GAU ADC node enabled, are not exposed to the privilege boundary; there the same defect only causes a silent overflow when the application itself passes an undersized buffer.<\/p>\n
The fix replaces the ad-hoc check with the shared adc_sequence_validate_buffer() helper (validating against num_channels * sizeof(uint16_t)), stores buffer_size \/ sizeof(uint16_t) in results_length, and corrects the loop bound to a post-decrement so exactly the available number of slots may be written.<\/p>\n","protected":false},"excerpt":{"rendered":"
The NXP GAU ADC driver (drivers\/adc\/adc_mcux_gau_adc.c) validated the caller-supplied sequence->buffer_size, which is expressed in bytes, against the number of active channels, which is a sample count<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-32745","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/32745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=32745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=32745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=32745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}