[PATCH net] gianfar: fix memory leak in gfar_parse_group error paths

[Rosen Penev <rosenp@gmail.com>]

In gfar_parse_group, if any allocation in the irqinfo[] loop fails,
or if of_iomap fails, or if the IRQ parsing fails, the already-
allocated irqinfo[] entries and mapped regs are not freed.  The
caller's free_gfar_dev cannot clean them up because priv->num_grps
is only incremented after a successful return.

Fix by adding an err_out label that frees all successfully allocated
irqinfo entries and unmaps regs if mapped.  Track the number of
allocated entries with 'allocated' and propagate the correct error
code.

Fixes: 46ceb60ca80fa ("gianfar: Add Multiple group Support")
Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/net/ethernet/freescale/gianfar.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 3271de5844f84..12ebb207be0be 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -502,17 +502,19 @@ static int gfar_parse_group(struct device_node *np,
 			    struct gfar_private *priv, const char *model)
 {
 	struct gfar_priv_grp *grp = &priv->gfargrp[priv->num_grps];
-	int i;
+	int err = -ENOMEM;
+	int i, allocated = 0;
 
 	for (i = 0; i < GFAR_NUM_IRQS; i++) {
 		grp->irqinfo[i] = kzalloc_obj(struct gfar_irqinfo);
 		if (!grp->irqinfo[i])
-			return -ENOMEM;
+			goto err_out;
+		allocated++;
 	}
 
 	grp->regs = of_iomap(np, 0);
 	if (!grp->regs)
-		return -ENOMEM;
+		goto err_out;
 
 	gfar_irq(grp, TX)->irq = irq_of_parse_and_map(np, 0);
 
@@ -522,8 +524,10 @@ static int gfar_parse_group(struct device_node *np,
 		gfar_irq(grp, ER)->irq = irq_of_parse_and_map(np, 2);
 		if (!gfar_irq(grp, TX)->irq ||
 		    !gfar_irq(grp, RX)->irq ||
-		    !gfar_irq(grp, ER)->irq)
-			return -EINVAL;
+		    !gfar_irq(grp, ER)->irq) {
+			err = -EINVAL;
+			goto err_out;
+		}
 	}
 
 	grp->priv = priv;
@@ -567,6 +571,13 @@ static int gfar_parse_group(struct device_node *np,
 	priv->num_grps++;
 
 	return 0;
+
+err_out:
+	for (i = 0; i < allocated; i++)
+		kfree(grp->irqinfo[i]);
+	if (grp->regs)
+		iounmap(grp->regs);
+	return err;
 }
 
 /* Reads the controller's registers to determine what interface
-- 
2.54.0