Messages in this thread Patch in this message |  | | Subject | [PATCH] iio: accel: fxls8962af: clamp FIFO sample count | | From | "Shengzhuo Wei" <> | | Date | Thu, 06 Aug 2026 05:14:53 +0800 |
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fxls8962af_fifo_flush() copies the number of samples the device reports in its FIFO status register into an on-stack buffer
u16 buffer[FXLS8962AF_FIFO_LENGTH * 3];
which is sized for at most FXLS8962AF_FIFO_LENGTH (32) samples. The sample count is read from the BUF_STATUS register and only masked to its 6 valid bits:
count = reg & FXLS8962AF_BUF_STATUS_BUF_CNT;
so it can be 0..63, while the buffer holds 32. The only other limit, the watermark, is applied on the write path (fxls8962af_set_watermark) but not here on the read path. count samples are then transferred into buffer[]:
fxls8962af_fifo_transfer(data, buffer, count);
fxls8962af_fifo_transfer() reads count * 6 bytes through regmap, so a malfunctioning, malicious or counterfeit accelerometer (or an attacker tampering with the I2C/SPI bus) that reports up to 63 samples writes up to 378 bytes into the 192-byte buffer: a stack out-of-bounds write of up to 186 bytes that clobbers the stack canary, saved registers and the return address.
Clamp count to FXLS8962AF_FIFO_LENGTH, the number of samples buffer[] is sized for, before the transfer, mirroring the watermark clamp already done in fxls8962af_set_watermark(). A well-formed flush reports at most FXLS8962AF_FIFO_LENGTH samples, so legitimate devices are unaffected.
Fixes: 79e3a5bdd9ef ("iio: accel: fxls8962af: add hw buffered sampling") Cc: stable@vger.kernel.org Assisted-by: GLM:5.2 Signed-off-by: Shengzhuo Wei <me@cherr.cc> --- This series adds a single patch clamping the device-reported FIFO sample count in fxls8962af_fifo_flush(), mirroring the bmc150 fix (ce0e1cae2609). --- drivers/iio/accel/fxls8962af-core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/iio/accel/fxls8962af-core.c b/drivers/iio/accel/fxls8962af-core.c index d0c2a8daef0db964134ad10b25782b9f5752613d..3aa96adf3eef8ff525e65ceec9a371da82216ea4 100644 --- a/drivers/iio/accel/fxls8962af-core.c +++ b/drivers/iio/accel/fxls8962af-core.c @@ -966,6 +966,7 @@ static int fxls8962af_fifo_flush(struct iio_dev *indio_dev) } count = reg & FXLS8962AF_BUF_STATUS_BUF_CNT; + count = min_t(u8, count, FXLS8962AF_FIFO_LENGTH); if (!count) return 0; --- base-commit: 848acc8ffe1b7cd5f1bf427b93069becfebc2c9d change-id: 20260806-fxls8962af-fifo-c3812fd02eeb Best regards, -- Shengzhuo Wei <me@cherr.cc>
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