From: Eric Dumazet edumazet@google.com
[ Upstream commit 44bfa9c5e5f06c72540273813e4c66beb5a8c213 ]
Since IFLA_ALT_IFNAME is an NLA_STRING, we have no guarantee it is nul terminated.
We should use nla_strdup() instead of kstrdup(), since this helper will make sure not accessing out-of-bounds data.
BUG: KMSAN: uninit-value in strlen+0x5e/0xa0 lib/string.c:535 CPU: 1 PID: 19157 Comm: syz-executor.5 Not tainted 5.5.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x220 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 strlen+0x5e/0xa0 lib/string.c:535 kstrdup+0x7f/0x1a0 mm/util.c:59 rtnl_alt_ifname net/core/rtnetlink.c:3495 [inline] rtnl_linkprop+0x85d/0xc00 net/core/rtnetlink.c:3553 rtnl_newlinkprop+0x9d/0xb0 net/core/rtnetlink.c:3568 rtnetlink_rcv_msg+0x1153/0x1570 net/core/rtnetlink.c:5424 netlink_rcv_skb+0x451/0x650 net/netlink/af_netlink.c:2477 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5442 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1328 netlink_sendmsg+0x1248/0x14d0 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:639 [inline] sock_sendmsg net/socket.c:659 [inline] ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2330 ___sys_sendmsg net/socket.c:2384 [inline] __sys_sendmsg+0x451/0x5f0 net/socket.c:2417 __do_sys_sendmsg net/socket.c:2426 [inline] __se_sys_sendmsg+0x97/0xb0 net/socket.c:2424 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2424 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45b3b9 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff1c7b1ac78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007ff1c7b1b6d4 RCX: 000000000045b3b9 RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009cb R14: 00000000004cb3dd R15: 000000000075bf2c
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82 slab_alloc_node mm/slub.c:2774 [inline] __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4382 __kmalloc_reserve net/core/skbuff.c:141 [inline] __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:209 alloc_skb include/linux/skbuff.h:1049 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1174 [inline] netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:639 [inline] sock_sendmsg net/socket.c:659 [inline] ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2330 ___sys_sendmsg net/socket.c:2384 [inline] __sys_sendmsg+0x451/0x5f0 net/socket.c:2417 __do_sys_sendmsg net/socket.c:2426 [inline] __se_sys_sendmsg+0x97/0xb0 net/socket.c:2424 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2424 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 36fbf1e52bd3 ("net: rtnetlink: add linkprop commands to add and delete alternative ifnames") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Jiri Pirko jiri@mellanox.com Reported-by: syzbot syzkaller@googlegroups.com Reviewed-by: Jiri Pirko jiri@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/rtnetlink.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-)
--- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3499,27 +3499,25 @@ static int rtnl_alt_ifname(int cmd, stru if (err) return err;
- alt_ifname = nla_data(attr); + alt_ifname = nla_strdup(attr, GFP_KERNEL); + if (!alt_ifname) + return -ENOMEM; + if (cmd == RTM_NEWLINKPROP) { - alt_ifname = kstrdup(alt_ifname, GFP_KERNEL); - if (!alt_ifname) - return -ENOMEM; err = netdev_name_node_alt_create(dev, alt_ifname); - if (err) { - kfree(alt_ifname); - return err; - } + if (!err) + alt_ifname = NULL; } else if (cmd == RTM_DELLINKPROP) { err = netdev_name_node_alt_destroy(dev, alt_ifname); - if (err) - return err; } else { - WARN_ON(1); - return 0; + WARN_ON_ONCE(1); + err = -EINVAL; }
- *changed = true; - return 0; + kfree(alt_ifname); + if (!err) + *changed = true; + return err; }
static int rtnl_linkprop(int cmd, struct sk_buff *skb, struct nlmsghdr *nlh,