remoteproc: pru: Fix potential NULL pointer dereference in pru_rproc_set_ctable()

pru_rproc_set_ctable() accessed rproc->priv before the IS_ERR_OR_NULL
check, which could lead to a null pointer dereference. Move the pru
assignment, ensuring we never dereference a NULL rproc pointer.

Fixes: 1028534 ("remoteproc: pru: Add pru_rproc_set_ctable() function")
Cc: [email protected]
Signed-off-by: Zhen Ni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mathieu Poirier <[email protected]>

Author: nizhen-t

drivers/remoteproc/pru_rproc.c

@@ -340,7 +340,7 @@ EXPORT_SYMBOL_GPL(pru_rproc_put);
  */
 int pru_rproc_set_ctable(struct rproc *rproc, enum pru_ctable_idx c, u32 addr)
 {
-	struct pru_rproc *pru = rproc->priv;
+	struct pru_rproc *pru;
 	unsigned int reg;
 	u32 mask, set;
 	u16 idx;
@@ -352,6 +352,7 @@ int pru_rproc_set_ctable(struct rproc *rproc, enum pru_ctable_idx c, u32 addr)
 	if (!rproc->dev.parent || !is_pru_rproc(rproc->dev.parent))
 		return -ENODEV;
 
+	pru = rproc->priv;
 	/* pointer is 16 bit and index is 8-bit so mask out the rest */
 	idx_mask = (c >= PRU_C28) ? 0xFFFF : 0xFF;