From: Taehee Yoo <ap420073@xxxxxxxxx>
[ Upstream commit 1eb1f43a6e37282348a41e3d68f5e9a6a4359212 ]
In the rmnet_changelink(), it uses IFLA_LINK without checking
NULL pointer.
tb[IFLA_LINK] could be NULL pointer.
So, NULL-ptr-deref could occur.
rmnet already has a lower interface (real_dev).
So, after this patch, rmnet_changelink() does not use IFLA_LINK anymore.
Test commands:
modprobe rmnet
ip link add dummy0 type dummy
ip link add rmnet0 link dummy0 type rmnet mux_id 1
ip link set rmnet0 type rmnet mux_id 2
Splat looks like:
[ 90.578726][ T1131] general protection fault, probably for non-canonical address 0xdffffc0000000000I
[ 90.581121][ T1131] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
[ 90.582380][ T1131] CPU: 2 PID: 1131 Comm: ip Not tainted 5.6.0-rc1+ #447
[ 90.584285][ T1131] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 90.587506][ T1131] RIP: 0010:rmnet_changelink+0x5a/0x8a0 [rmnet]
[ 90.588546][ T1131] Code: 83 ec 20 48 c1 ea 03 80 3c 02 00 0f 85 6f 07 00 00 48 8b 5e 28 48 b8 00 00 00 00 00 0
[ 90.591447][ T1131] RSP: 0018:ffff8880ce78f1b8 EFLAGS: 00010247
[ 90.592329][ T1131] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff8880ce78f8b0
[ 90.593253][ T1131] RDX: 0000000000000000 RSI: ffff8880ce78f4a0 RDI: 0000000000000004
[ 90.594058][ T1131] RBP: ffff8880cf543e00 R08: 0000000000000002 R09: 0000000000000002
[ 90.594859][ T1131] R10: ffffffffc0586a40 R11: 0000000000000000 R12: ffff8880ca47c000
[ 90.595690][ T1131] R13: ffff8880ca47c000 R14: ffff8880cf545000 R15: 0000000000000000
[ 90.596553][ T1131] FS: 00007f21f6c7e0c0(0000) GS:ffff8880da400000(0000) knlGS:0000000000000000
[ 90.597504][ T1131] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 90.599418][ T1131] CR2: 0000556e413db458 CR3: 00000000c917a002 CR4: 00000000000606e0
[ 90.600289][ T1131] Call Trace:
[ 90.600631][ T1131] __rtnl_newlink+0x922/0x1270
[ 90.601194][ T1131] ? lock_downgrade+0x6e0/0x6e0
[ 90.601724][ T1131] ? rtnl_link_unregister+0x220/0x220
[ 90.602309][ T1131] ? lock_acquire+0x164/0x3b0
[ 90.602784][ T1131] ? is_bpf_image_address+0xff/0x1d0
[ 90.603331][ T1131] ? rtnl_newlink+0x4c/0x90
[ 90.603810][ T1131] ? kernel_text_address+0x111/0x140
[ 90.604419][ T1131] ? __kernel_text_address+0xe/0x30
[ 90.604981][ T1131] ? unwind_get_return_address+0x5f/0xa0
[ 90.605616][ T1131] ? create_prof_cpu_mask+0x20/0x20
[ 90.606304][ T1131] ? arch_stack_walk+0x83/0xb0
[ 90.606985][ T1131] ? stack_trace_save+0x82/0xb0
[ 90.607656][ T1131] ? stack_trace_consume_entry+0x160/0x160
[ 90.608503][ T1131] ? deactivate_slab.isra.78+0x2c5/0x800
[ 90.609336][ T1131] ? kasan_unpoison_shadow+0x30/0x40
[ 90.610096][ T1131] ? kmem_cache_alloc_trace+0x135/0x350
[ 90.610889][ T1131] ? rtnl_newlink+0x4c/0x90
[ 90.611512][ T1131] rtnl_newlink+0x65/0x90
[ ... ]
Fixes: 23790ef12082 ("net: qualcomm: rmnet: Allow to configure flags for existing devices")
Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index 0fb9375b4f69e..ad46f5aadc0ab 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
@@ -309,10 +309,8 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
if (!dev)
return -ENODEV;
- real_dev = __dev_get_by_index(dev_net(dev),
- nla_get_u32(tb[IFLA_LINK]));
-
- if (!real_dev || !rmnet_is_real_dev_registered(real_dev))
+ real_dev = priv->real_dev;
+ if (!rmnet_is_real_dev_registered(real_dev))
return -ENODEV;
port = rmnet_get_port_rtnl(real_dev);
--
2.20.1
