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uru4000: Prevent a buffer overflow on reading the device image data

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num_lines comes from the device for each block and is summed into
the source row index (r) and destination byte offset (to).
Neither the per-block value nor the running totals are otherwise bound,
so a malicious device could drive the copy past the source
(IMAGE_HEIGHT rows) or destination buffer.

Reported by: Keith Linneman (LinnemanLabs)
This commit is contained in:
Marco Trevisan (Treviño)
2026-07-13 08:13:46 +00:00
committed by Marco Trevisan
parent 63be3884d6
commit ad8a6f6b17
1 changed files with 14 additions and 2 deletions
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libfprint/drivers/uru4000.c
+14 -2
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@@ -681,10 +681,10 @@ calc_dev2 (struct uru4k_image *img)
static void
imaging_run_state (FpiSsm *ssm, FpDevice *_dev)
{
g_autoptr(FpImage) fpimg = NULL;
FpImageDevice *dev = FP_IMAGE_DEVICE (_dev);
FpiDeviceUru4000 *self = FPI_DEVICE_URU4000 (_dev);
struct uru4k_image *img = self->img_data;
FpImage *fpimg;
uint32_t key;
uint8_t flags, num_lines;
int i, r, to, dev2;
@@ -798,6 +798,17 @@ imaging_run_state (FpiSsm *ssm, FpDevice *_dev)
num_lines = img->block_info[i].num_lines;
if (num_lines == 0)
break;
if ((size_t) r + num_lines > IMAGE_HEIGHT ||
(size_t) to + (size_t) num_lines * IMAGE_WIDTH > fpimg->width * fpimg->height)
{
fp_err ("bad captured image: block %d (%d lines) overflows buffer",
i, num_lines);
fpi_ssm_mark_failed (ssm,
fpi_device_error_new (FP_DEVICE_ERROR_PROTO));
return;
}
memcpy (&fpimg->data[to], &img->data[r][0],
num_lines * IMAGE_WIDTH);
if (!(flags & BLOCKF_NOT_PRESENT))
@@ -814,7 +825,8 @@ imaging_run_state (FpiSsm *ssm, FpDevice *_dev)
*/
if (self->profile->image_not_flipped)
fpimg->flags |= FPI_IMAGE_V_FLIPPED | FPI_IMAGE_H_FLIPPED;
fpi_image_device_image_captured (dev, fpimg);
fpi_image_device_image_captured (dev, g_steal_pointer (&fpimg));
if (self->activate_state == FPI_IMAGE_DEVICE_STATE_CAPTURE)
fpi_ssm_jump_to_state (ssm, IMAGING_CAPTURE);