{"id":"CVE-2026-64502","summary":"iio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices","details":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices\n\nad_sigma_delta_clear_pending_event() falls through to the status register\nread path for devices with has_registers = false and no rdy_gpiod. For\nsuch devices, ad_sd_read_reg() skips the address byte entirely and clocks\nraw MISO bytes with no address phase — making it byte-for-byte identical\nto reading conversion data. If a pending conversion result is present,\nthis partially consumes it and corrupts the data stream for the subsequent\nad_sd_read_reg() call in ad_sigma_delta_single_conversion().\n\nFurthermore, with num_resetclks = 0 on these devices, data_read_len\nevaluates to 0. If the clocked byte has bit 7 clear, pending_event is set\nand the code attempts memset(data + 2, 0xff, 0 - 1), overflowing to\nSIZE_MAX and corrupting the heap.\n\nFix by returning 0 immediately when neither rdy_gpiod nor has_registers\nis set. This is safe for all current registerless devices: ad7191 and\nad7780 (with powerdown GPIO) are reset between conversions by CS\ndeassertion, so there is no stale result to drain; ad7780 (without\npowerdown GPIO) and max11205 are continuously-converting and cycle ~DRDY\nat the output data rate regardless of whether the previous result was\nread, so the next falling edge fires naturally.\n\nA future registerless device that holds ~DRDY asserted until data is read\nwould be broken by this early return and would require either\nnum_resetclks set or a rdy-gpio.\n\nThe same heap corruption is reachable on any device with rdy_gpiod set\nbut num_resetclks = 0: if the GPIO indicates a pending event, the drain\npath executes memset(data + 2, 0xff, 0 - 1) regardless of has_registers.\nAdd an explicit data_read_len == 0 guard after the pending event check;\nthe stale result is then consumed by the first ad_sd_read_reg() call in\nad_sigma_delta_single_conversion().","modified":"2026-07-28T04:03:09.093929530Z","published":"2026-07-25T08:51:57.477Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64502.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3394e0b3328422431cadaf314fa58d3717ed4936"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3bceb26dfaf7ba805b459e41c1d0ba916862dade"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91bc6767a4f55dc470d8a56b55b9f2ea09094efe"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64502.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64502"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"132d44dc6966c1cf841ffe0f6f048165687e870b"},{"fixed":"3394e0b3328422431cadaf314fa58d3717ed4936"},{"fixed":"3bceb26dfaf7ba805b459e41c1d0ba916862dade"},{"fixed":"91bc6767a4f55dc470d8a56b55b9f2ea09094efe"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64502.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.14.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64502.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}