[PATCH] accel/ivpu: Reject firmware log with size smaller than header

[Jhonraushan <raushan.jhon@gmail.com>]

fw_log_from_bo() validates the tracing buffer header_size and that the
log fits within the BO, but never checks that log->size is at least
log->header_size. fw_log_print_buffer() then computes:

  u32 data_size = log->size - log->header_size;

which underflows to a near-U32_MAX value when firmware reports a log whose
size is smaller than its header. That huge data_size defeats the
log_start/log_end bounds clamps added by commit dd1311bcf0e6 ("accel/ivpu:
Add bounds checks for firmware log indices"), so fw_log_print_lines() reads
far past the small real data region of the BO. A size of 0 also makes
fw_log_from_bo() advance the offset by 0, causing the callers to loop
forever on the same header.

Reject logs whose size is smaller than the header (which also rejects
size == 0).

Fixes: d4e4257afa6e ("accel/ivpu: Add firmware tracing support")
Cc: stable@vger.kernel.org
Signed-off-by: Jhonraushan <raushan.jhon@gmail.com>
---
 drivers/accel/ivpu/ivpu_fw_log.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/accel/ivpu/ivpu_fw_log.c b/drivers/accel/ivpu/ivpu_fw_log.c
index 275baf844b56..716467aa3156 100644
--- a/drivers/accel/ivpu/ivpu_fw_log.c
+++ b/drivers/accel/ivpu/ivpu_fw_log.c
@@ -43,6 +43,10 @@ static int fw_log_from_bo(struct ivpu_device *vdev, struct ivpu_bo *bo, u32 *off
 		ivpu_dbg(vdev, FW_BOOT, "Invalid header size 0x%x\n", log->header_size);
 		return -EINVAL;
 	}
+	if (log->size < log->header_size) {
+		ivpu_dbg(vdev, FW_BOOT, "Invalid log size 0x%x\n", log->size);
+		return -EINVAL;
+	}
 	if ((char *)log + log->size > (char *)ivpu_bo_vaddr(bo) + ivpu_bo_size(bo)) {
 		ivpu_dbg(vdev, FW_BOOT, "Invalid log size 0x%x\n", log->size);
 		return -EINVAL;
-- 
2.53.0