[PATCH v2 1/2] iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and_mask()

[Andy Shevchenko]

From: Yang Yingliang <yangyingliang@xxxxxxxxxx>

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@xxxxxxxxxx>
Fixes: ee708e6baacd ("iio: buffer: introduce support for attaching more IIO buffers")
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/iio/industrialio-buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 4209e933ab80..bb181d11573c 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1616,7 +1616,7 @@ 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;
 		}
 	}
-- 
2.33.0