iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and_mask()

[ Upstream commit 09776d9374e635b1580b3736c19b95b788fbaa85 ]

When __iio_buffer_alloc_sysfs_and_mask() failed, 'unwind_idx' should be
set to 'i - 1' to prevent double-free when cleanup resources.

BUG: KASAN: double-free or invalid-free in __iio_buffer_free_sysfs_and_mask+0x32/0xb0 [industrialio]
Call Trace:
 kfree+0x117/0x4c0
 __iio_buffer_free_sysfs_and_mask+0x32/0xb0 [industrialio]
 iio_buffers_alloc_sysfs_and_mask+0x60d/0x1570 [industrialio]
 __iio_device_register+0x483/0x1a30 [industrialio]
 ina2xx_probe+0x625/0x980 [ina2xx_adc]

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: ee708e6baacd ("iio: buffer: introduce support for attaching more IIO buffers")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211013094923.2473-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 7f4e3ce..2f98ba7 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1624,7 +1624,7 @@ int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
                buffer = iio_dev_opaque->attached_buffers[i];
                ret = __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, i);
                if (ret) {
-                       unwind_idx = i;
+                       unwind_idx = i - 1;
                        goto error_unwind_sysfs_and_mask;
                }
        }