In the Linux kernel, the following vulnerability has been resolved:
iio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices
ad_sigma_delta_clear_pending_event() falls through to the status register
read path for devices with has_registers = false and no rdy_gpiod. For
such devices, ad_sd_read_reg() skips the address byte entirely and clocks
raw MISO bytes with no address phase — making it byte-for-byte identical
to reading conversion data. If a pending conversion result is present,
this partially consumes it and corrupts the data stream for the subsequent
ad_sd_read_reg() call in ad_sigma_delta_single_conversion().
Furthermore, with num_resetclks = 0 on these devices, data_read_len
evaluates to 0. If the clocked byte has bit 7 clear, pending_event is set
and the code attempts memset(data + 2, 0xff, 0 - 1), overflowing to
SIZE_MAX and corrupting the heap.
Fix by returning 0 immediately when neither rdy_gpiod nor has_registers
is set. This is safe for all current registerless devices: ad7191 and
ad7780 (with powerdown GPIO) are reset between conversions by CS
deassertion, so there is no stale result to drain; ad7780 (without
powerdown GPIO) and max11205 are continuously-converting and cycle ~DRDY
at the output data rate regardless of whether the previous result was
read, so the next falling edge fires naturally.
A future registerless device that holds ~DRDY asserted until data is read
would be broken by this early return and would require either
num_resetclks set or a rdy-gpio.
The same heap corruption is reachable on any device with rdy_gpiod set
but num_resetclks = 0: if the GPIO indicates a pending event, the drain
path executes memset(data + 2, 0xff, 0 - 1) regardless of has_registers.
Add an explicit data_read_len == 0 guard after the pending event check;
the stale result is then consumed by the first ad_sd_read_reg() call in
ad_sigma_delta_single_conversion().
Metrics
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Linux |
|
No data.
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References
History
Sat, 25 Jul 2026 09:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: iio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices ad_sigma_delta_clear_pending_event() falls through to the status register read path for devices with has_registers = false and no rdy_gpiod. For such devices, ad_sd_read_reg() skips the address byte entirely and clocks raw MISO bytes with no address phase — making it byte-for-byte identical to reading conversion data. If a pending conversion result is present, this partially consumes it and corrupts the data stream for the subsequent ad_sd_read_reg() call in ad_sigma_delta_single_conversion(). Furthermore, with num_resetclks = 0 on these devices, data_read_len evaluates to 0. If the clocked byte has bit 7 clear, pending_event is set and the code attempts memset(data + 2, 0xff, 0 - 1), overflowing to SIZE_MAX and corrupting the heap. Fix by returning 0 immediately when neither rdy_gpiod nor has_registers is set. This is safe for all current registerless devices: ad7191 and ad7780 (with powerdown GPIO) are reset between conversions by CS deassertion, so there is no stale result to drain; ad7780 (without powerdown GPIO) and max11205 are continuously-converting and cycle ~DRDY at the output data rate regardless of whether the previous result was read, so the next falling edge fires naturally. A future registerless device that holds ~DRDY asserted until data is read would be broken by this early return and would require either num_resetclks set or a rdy-gpio. The same heap corruption is reachable on any device with rdy_gpiod set but num_resetclks = 0: if the GPIO indicates a pending event, the drain path executes memset(data + 2, 0xff, 0 - 1) regardless of has_registers. Add an explicit data_read_len == 0 guard after the pending event check; the stale result is then consumed by the first ad_sd_read_reg() call in ad_sigma_delta_single_conversion(). | |
| Title | iio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-25T08:51:57.477Z
Reserved: 2026-07-19T15:36:31.793Z
Link: CVE-2026-64502
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.