The Goodix GT9xx input driver in drivers/input/input_gt911.c reads the touch point count from the controller's status register and masks it with GT911_TOUCH_POINTS_MSK (0x0F), yielding a value of 0..15. In gt911_process() that value is used directly as the loop bound for filling point_reg[], a stack array sized to CONFIG_INPUT_GT911_MAX_TOUCH_POINTS, whose Kconfig range is 1..5 with a default of 1. No other check constrains the count; the driver relied only on a comment asserting that the controller had been programmed at init to report no more points than configured.
Each loop iteration issues an I2C read of eight bytes straight into point_reg[i], so a controller that reports more points than the array holds causes up to 112 bytes of peer-supplied data to be written past the end of the array, over the stack frame of gt911_process() in the system workqueue thread. Two further loops then read out of bounds from the same array. Triggering it requires control of, or the ability to substitute, the I2C touch controller — plausible on the many supported boards where the GT9xx panel is a pluggable display module or shield rather than an on-PCB part; a spoofed device need only answer the init probes with a supported product ID and a checksum-valid config blob. The same overflow can also occur non-adversarially, with a GT9271-class panel that ignores the driver's touch-count programming and reports up to ten points, or with bus corruption of the single status byte.
The impact is an out-of-bounds stack write with fully attacker-chosen content executing at kernel privilege, i.e. potential control-flow hijack on the host MCU, in addition to out-of-bounds reads and crashes. The attack vector is physical/local hardware access only; there is no network, USB, or syscall path to the defect. The fix clamps the reported count with min() against CONFIG_INPUT_GT911_MAX_TOUCH_POINTS before any array indexing.
Each loop iteration issues an I2C read of eight bytes straight into point_reg[i], so a controller that reports more points than the array holds causes up to 112 bytes of peer-supplied data to be written past the end of the array, over the stack frame of gt911_process() in the system workqueue thread. Two further loops then read out of bounds from the same array. Triggering it requires control of, or the ability to substitute, the I2C touch controller — plausible on the many supported boards where the GT9xx panel is a pluggable display module or shield rather than an on-PCB part; a spoofed device need only answer the init probes with a supported product ID and a checksum-valid config blob. The same overflow can also occur non-adversarially, with a GT9271-class panel that ignores the driver's touch-count programming and reports up to ten points, or with bus corruption of the single status byte.
The impact is an out-of-bounds stack write with fully attacker-chosen content executing at kernel privilege, i.e. potential control-flow hijack on the host MCU, in addition to out-of-bounds reads and crashes. The attack vector is physical/local hardware access only; there is no network, USB, or syscall path to the defect. The fix clamps the reported count with min() against CONFIG_INPUT_GT911_MAX_TOUCH_POINTS before any array indexing.
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History
Sun, 11 Oct 2026 18:45:00 +0000
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| First Time appeared |
Zephyrproject
Zephyrproject zephyr |
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| Vendors & Products |
Zephyrproject
Zephyrproject zephyr |
Sun, 11 Oct 2026 17:30:00 +0000
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| Description | The Goodix GT9xx input driver in drivers/input/input_gt911.c reads the touch point count from the controller's status register and masks it with GT911_TOUCH_POINTS_MSK (0x0F), yielding a value of 0..15. In gt911_process() that value is used directly as the loop bound for filling point_reg[], a stack array sized to CONFIG_INPUT_GT911_MAX_TOUCH_POINTS, whose Kconfig range is 1..5 with a default of 1. No other check constrains the count; the driver relied only on a comment asserting that the controller had been programmed at init to report no more points than configured. Each loop iteration issues an I2C read of eight bytes straight into point_reg[i], so a controller that reports more points than the array holds causes up to 112 bytes of peer-supplied data to be written past the end of the array, over the stack frame of gt911_process() in the system workqueue thread. Two further loops then read out of bounds from the same array. Triggering it requires control of, or the ability to substitute, the I2C touch controller — plausible on the many supported boards where the GT9xx panel is a pluggable display module or shield rather than an on-PCB part; a spoofed device need only answer the init probes with a supported product ID and a checksum-valid config blob. The same overflow can also occur non-adversarially, with a GT9271-class panel that ignores the driver's touch-count programming and reports up to ten points, or with bus corruption of the single status byte. The impact is an out-of-bounds stack write with fully attacker-chosen content executing at kernel privilege, i.e. potential control-flow hijack on the host MCU, in addition to out-of-bounds reads and crashes. The attack vector is physical/local hardware access only; there is no network, USB, or syscall path to the defect. The fix clamps the reported count with min() against CONFIG_INPUT_GT911_MAX_TOUCH_POINTS before any array indexing. | |
| Title | Stack out-of-bounds write in the Goodix GT911 touch controller driver from an unvalidated device-reported touch point count | |
| Weaknesses | CWE-787 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: zephyr
Published:
Updated: 2026-10-11T17:14:53.339Z
Reserved: 2026-08-11T19:56:48.396Z
Link: CVE-2026-19576
No data.
Status : Received
Published: 2026-10-11T18:16:58.300
Modified: 2026-10-11T18:16:58.300
Link: CVE-2026-19576
No data.
OpenCVE Enrichment
Updated: 2026-10-11T18:30:18Z
Weaknesses