linux-kernel - [PATCH 4.14 062/110] mlxsw: spectrum_router: Fix error path in mlxsw_sp_vr

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Date:   Wed,  7 Mar 2018 11:38:45 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiri Pirko <jiri@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.14 062/110] mlxsw: spectrum_router: Fix error path in mlxsw_sp_vr_create

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Pirko <jiri@...lanox.com>


[ 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.

Fixes: 76610ebbde18 ("mlxsw: spectrum_router: Refactor virtual router handling")
Fixes: a3d9bc506d64 ("mlxsw: spectrum_router: Extend virtual routers with IPv6 support")
Fixes: d42b0965b1d4 ("mlxsw: spectrum_router: Add multicast routes notification handling functionality")
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
Reviewed-by: Ido Schimmel <idosch@...lanox.com>
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c |   19 ++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -729,26 +729,29 @@ static struct mlxsw_sp_fib *mlxsw_sp_vr_
 static struct mlxsw_sp_vr *mlxsw_sp_vr_create(struct mlxsw_sp *mlxsw_sp,
 					      u32 tb_id)
 {
+	struct mlxsw_sp_fib *fib4;
+	struct mlxsw_sp_fib *fib6;
 	struct mlxsw_sp_vr *vr;
 	int err;
 
 	vr = mlxsw_sp_vr_find_unused(mlxsw_sp);
 	if (!vr)
 		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->fib4 = fib4;
+	vr->fib6 = fib6;
 	vr->tb_id = tb_id;
 	return vr;
 
 err_fib6_create:
-	mlxsw_sp_fib_destroy(vr->fib4);
-	vr->fib4 = NULL;
+	mlxsw_sp_fib_destroy(fib4);
 	return ERR_PTR(err);
 }