Patch "mlxsw: spectrum_router: Fix error path in mlxsw_sp_vr_create" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

mlxsw: spectrum_router: Fix error path in mlxsw_sp_vr_create

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mlxsw-spectrum_router-fix-error-path-in-mlxsw_sp_vr_create.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jiri Pirko <[email protected]>
Date: Tue, 13 Feb 2018 11:22:42 +0100
Subject: mlxsw: spectrum_router: Fix error path in mlxsw_sp_vr_create

From: Jiri Pirko <[email protected]>

[ Upstream commit 0f2d2b2736b08dafa3bde31d048750fbc8df3a31 ]

Since mlxsw_sp_fib_create() and mlxsw_sp_mr_table_create() use ERR_PTR macro to propagate int err through return of a pointer, the return value is not NULL in case of failure. So if one of the calls fails, one of vr->fib4, vr->fib6 or vr->mr4_table is not NULL and mlxsw_sp_vr_is_used wrongly assumes
that vr is in use which leads to crash like following one:

[ 1293.949291] BUG: unable to handle kernel NULL pointer dereference at 00000000000006c9
[ 1293.952729] IP: mlxsw_sp_mr_table_flush+0x15/0x70 [mlxsw_spectrum]

Fix this by using local variables to hold the pointers and set vr->* only in case everything went fine.

---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c |   32 ++++++++++--------
 1 file changed, 18 insertions(+), 14 deletions(-)

@@ -737,6 +737,9 @@ static struct mlxsw_sp_vr *mlxsw_sp_vr_c
 					      u32 tb_id,
 					      struct netlink_ext_ack *extack)
 {
+	struct mlxsw_sp_mr_table *mr4_table;
+	struct mlxsw_sp_fib *fib4;
+	struct mlxsw_sp_fib *fib6;
 	struct mlxsw_sp_vr *vr;
 	int err;
 

@@ -745,29 +748,30 @@ static struct mlxsw_sp_vr *mlxsw_sp_vr_c
 		NL_SET_ERR_MSG(extack, "spectrum: Exceeded number of supported virtual routers");
 		return ERR_PTR(-EBUSY);
 	}
-	vr->fib4 = mlxsw_sp_fib_create(vr, MLXSW_SP_L3_PROTO_IPV4);
-	if (IS_ERR(vr->fib4))
-		return ERR_CAST(vr->fib4);
-	vr->fib6 = mlxsw_sp_fib_create(vr, MLXSW_SP_L3_PROTO_IPV6);
-	if (IS_ERR(vr->fib6)) {
-		err = PTR_ERR(vr->fib6);
+	fib4 = mlxsw_sp_fib_create(vr, MLXSW_SP_L3_PROTO_IPV4);
+	if (IS_ERR(fib4))
+		return ERR_CAST(fib4);
+	fib6 = mlxsw_sp_fib_create(vr, MLXSW_SP_L3_PROTO_IPV6);
+	if (IS_ERR(fib6)) {
+		err = PTR_ERR(fib6);
 		goto err_fib6_create;
 	}
-	vr->mr4_table = mlxsw_sp_mr_table_create(mlxsw_sp, vr->id,
-						 MLXSW_SP_L3_PROTO_IPV4);
-	if (IS_ERR(vr->mr4_table)) {
-		err = PTR_ERR(vr->mr4_table);
+	mr4_table = mlxsw_sp_mr_table_create(mlxsw_sp, vr->id,
+					     MLXSW_SP_L3_PROTO_IPV4);
+	if (IS_ERR(mr4_table)) {
+		err = PTR_ERR(mr4_table);
 		goto err_mr_table_create;
 	}
+	vr->fib4 = fib4;
+	vr->fib6 = fib6;
+	vr->mr4_table = mr4_table;
 	vr->tb_id = tb_id;
 	return vr;
 
 err_mr_table_create:
-	mlxsw_sp_fib_destroy(vr->fib6);
-	vr->fib6 = NULL;
+	mlxsw_sp_fib_destroy(fib6);
 err_fib6_create:
-	mlxsw_sp_fib_destroy(vr->fib4);
-	vr->fib4 = NULL;
+	mlxsw_sp_fib_destroy(fib4);
 	return ERR_PTR(err);
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/mlxsw-spectrum_router-fix-error-path-in-mlxsw_sp_vr_create.patch queue-4.15/mlxsw-spectrum_router-do-not-unconditionally-clear-route-offload-indication.patch queue-4.15/net-sched-report-if-filter-is-too-large-to-dump.patch queue-4.15/mlxsw-spectrum_switchdev-check-success-of-fdb-add-operation.patch