3.16.83-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit 9e99bfefdbce2e23ef37487a3bcb4adf90a791d1 upstream.
1) syzbot reported an uninit-value in bond_neigh_setup() [1]
bond_neigh_setup() uses a temporary on-stack 'struct neigh_parms parms', but only clears parms.neigh_setup field.
A stacked bonding device would then enter bond_neigh_setup() and read garbage from parms->dev.
If we get really unlucky and garbage is matching @dev, then we could recurse and eventually crash.
Let's make sure the whole structure is cleared to avoid surprises.
2) bond_neigh_setup() can be called while another cpu manipulates the master device, removing or adding a slave. We need at least rcu protection to prevent use-after-free.
Note: Prior code does not support a stack of bonding devices, this patch does not attempt to fix this, and leave a comment instead.
[1]
BUG: KMSAN: uninit-value in bond_neigh_setup+0xa4/0x110 drivers/net/bonding/bond_main.c:3655 CPU: 0 PID: 11256 Comm: syz-executor.0 Not tainted 5.4.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x220 lib/dump_stack.c:118 kmsan_report+0x128/0x220 mm/kmsan/kmsan_report.c:108 __msan_warning+0x57/0xa0 mm/kmsan/kmsan_instr.c:245 bond_neigh_setup+0xa4/0x110 drivers/net/bonding/bond_main.c:3655 bond_neigh_init+0x216/0x4b0 drivers/net/bonding/bond_main.c:3626 ___neigh_create+0x169e/0x2c40 net/core/neighbour.c:613 __neigh_create+0xbd/0xd0 net/core/neighbour.c:674 ip6_finish_output2+0x149a/0x2670 net/ipv6/ip6_output.c:113 __ip6_finish_output+0x83d/0x8f0 net/ipv6/ip6_output.c:142 ip6_finish_output+0x2db/0x420 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0x5d3/0x720 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] mld_sendpack+0xebd/0x13d0 net/ipv6/mcast.c:1682 mld_send_cr net/ipv6/mcast.c:1978 [inline] mld_ifc_timer_expire+0x116b/0x1680 net/ipv6/mcast.c:2477 call_timer_fn+0x232/0x530 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers+0xd60/0x1270 kernel/time/timer.c:1773 run_timer_softirq+0x2d/0x50 kernel/time/timer.c:1786 __do_softirq+0x4a1/0x83a kernel/softirq.c:293 invoke_softirq kernel/softirq.c:375 [inline] irq_exit+0x230/0x280 kernel/softirq.c:416 exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:536 smp_apic_timer_interrupt+0x48/0x70 arch/x86/kernel/apic/apic.c:1138 apic_timer_interrupt+0x2e/0x40 arch/x86/entry/entry_64.S:835 </IRQ> RIP: 0010:kmsan_free_page+0x18d/0x1c0 mm/kmsan/kmsan_shadow.c:439 Code: 4c 89 ff 44 89 f6 e8 82 0d ee ff 65 ff 0d 9f 26 3b 60 65 8b 05 98 26 3b 60 85 c0 75 24 e8 5b f6 35 ff 4c 89 6d d0 ff 75 d0 9d <48> 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 0f 0b 0f 0b 0f RSP: 0018:ffffb328034af818 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: ffffe2d7471f8360 RCX: 0000000000000000 RDX: ffffffffadea7000 RSI: 0000000000000004 RDI: ffff93496fcda104 RBP: ffffb328034af850 R08: ffff934a47e86d00 R09: ffff93496fc41900 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000246 R14: 0000000000000000 R15: ffffe2d7472225c0 free_pages_prepare mm/page_alloc.c:1138 [inline] free_pcp_prepare mm/page_alloc.c:1230 [inline] free_unref_page_prepare+0x1d9/0x770 mm/page_alloc.c:3025 free_unref_page mm/page_alloc.c:3074 [inline] free_the_page mm/page_alloc.c:4832 [inline] __free_pages+0x154/0x230 mm/page_alloc.c:4840 __vunmap+0xdac/0xf20 mm/vmalloc.c:2277 __vfree mm/vmalloc.c:2325 [inline] vfree+0x7c/0x170 mm/vmalloc.c:2355 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:883 [inline] get_entries net/ipv6/netfilter/ip6_tables.c:1041 [inline] do_ip6t_get_ctl+0xfa4/0x1030 net/ipv6/netfilter/ip6_tables.c:1709 nf_sockopt net/netfilter/nf_sockopt.c:104 [inline] nf_getsockopt+0x481/0x4e0 net/netfilter/nf_sockopt.c:122 ipv6_getsockopt+0x264/0x510 net/ipv6/ipv6_sockglue.c:1400 tcp_getsockopt+0x1c6/0x1f0 net/ipv4/tcp.c:3688 sock_common_getsockopt+0x13f/0x180 net/core/sock.c:3110 __sys_getsockopt+0x533/0x7b0 net/socket.c:2129 __do_sys_getsockopt net/socket.c:2144 [inline] __se_sys_getsockopt+0xe1/0x100 net/socket.c:2141 __x64_sys_getsockopt+0x62/0x80 net/socket.c:2141 do_syscall_64+0xb6/0x160 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d20a Code: b8 34 01 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 8d 8b fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 6a 8b fb ff c3 66 0f 1f 84 00 00 00 00 00 RSP: 002b:0000000000a6f618 EFLAGS: 00000212 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 0000000000a6f640 RCX: 000000000045d20a RDX: 0000000000000041 RSI: 0000000000000029 RDI: 0000000000000003 RBP: 0000000000717cc0 R08: 0000000000a6f63c R09: 0000000000004000 R10: 0000000000a6f740 R11: 0000000000000212 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000000000029 R15: 0000000000715b00
Local variable description: ----parms@bond_neigh_init Variable was created at: bond_neigh_init+0x8c/0x4b0 drivers/net/bonding/bond_main.c:3617 bond_neigh_init+0x8c/0x4b0 drivers/net/bonding/bond_main.c:3617
Fixes: 9918d5bf329d ("bonding: modify only neigh_parms owned by us") Fixes: 234bcf8a499e ("net/bonding: correctly proxy slave neigh param setup ndo function") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Cc: Jay Vosburgh j.vosburgh@gmail.com Cc: Veaceslav Falico vfalico@gmail.com Cc: Andy Gospodarek andy@greyhouse.net Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/net/bonding/bond_main.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-)
--- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3421,24 +3421,35 @@ static int bond_neigh_init(struct neighb const struct net_device_ops *slave_ops; struct neigh_parms parms; struct slave *slave; - int ret; + int ret = 0;
- slave = bond_first_slave(bond); + rcu_read_lock(); + slave = bond_first_slave_rcu(bond); if (!slave) - return 0; + goto out; slave_ops = slave->dev->netdev_ops; if (!slave_ops->ndo_neigh_setup) - return 0; + goto out;
- parms.neigh_setup = NULL; + /* TODO: find another way [1] to implement this. + * Passing a zeroed structure is fragile, + * but at least we do not pass garbage. + * + * [1] One way would be that ndo_neigh_setup() never touch + * struct neigh_parms, but propagate the new neigh_setup() + * back to ___neigh_create() / neigh_parms_alloc() + */ + memset(&parms, 0, sizeof(parms)); ret = slave_ops->ndo_neigh_setup(slave->dev, &parms); - if (ret) - return ret;
- if (!parms.neigh_setup) - return 0; + if (ret) + goto out;
- return parms.neigh_setup(n); + if (parms.neigh_setup) + ret = parms.neigh_setup(n); +out: + rcu_read_unlock(); + return ret; }
/*