Messages in this thread | | | Date | Wed, 26 Aug 2009 10:27:09 +0200 | From | Ingo Molnar <> | Subject | Re: [kmemcheck] WARNING: kmemcheck: Caught 32-bit read from uninitialized memory, in sock_init_data() |
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* Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Vegard Nossum a ??crit : > > 2009/8/26 Ingo Molnar <mingo@elte.hu>: > >> -tip testing found another kmemcheck warning: > >> > >> calling netlink_proto_init+0x0/0x1b0 @ 1 > >> NET: Registered protocol family 16 > >> initcall netlink_proto_init+0x0/0x1b0 returned 0 after 39062 usecs > >> calling olpc_init+0x0/0x110 @ 1 > >> WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f5c38304) > >> 0100000002000000000000000000000000000000ad4eaddeffffffffffffffff > >> i i i i i i u u i i i i i i i i i i i i i i i i i i i i i i i i > >> ^ > >> > >> Pid: 1, comm: swapper Not tainted (2.6.31-rc7-tip-01170-gaaea9cf-dirty #24) P4DC6 > >> EIP: 0060:[<c15c8ab1>] EFLAGS: 00010286 CPU: 0 > >> EIP is at sock_init_data+0xe1/0x220 > >> EAX: 0001b000 EBX: f606196c ECX: 00000000 EDX: c1a148d2 > >> ESI: f6061800 EDI: f5c38300 EBP: f606ef0c ESP: c1ceb9ac > >> DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 > >> CR0: 8005003b CR2: f60a8108 CR3: 01a61000 CR4: 000006f0 > >> DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > >> DR6: ffff4ff0 DR7: 00000400 > >> [<c15fac15>] __netlink_create+0x35/0xa0 > >> [<c15fd01a>] netlink_kernel_create+0x5a/0x180 > >> [<c15df55e>] rtnetlink_net_init+0x1e/0x50 > >> [<c15d130a>] register_pernet_operations+0x6a/0xf0 > >> [<c15d14fe>] register_pernet_subsys+0x1e/0x30 > >> [<c1b3d84c>] rtnetlink_init+0x4c/0x100 > >> [<c1b3e105>] netlink_proto_init+0x105/0x1b0 > >> [<c1001037>] do_one_initcall+0x27/0x170 > >> [<c1afea97>] kernel_init+0x157/0x210 > >> [<c10039a7>] kernel_thread_helper+0x7/0x10 > >> [<ffffffff>] 0xffffffff > >> initcall olpc_init+0x0/0x110 returned 0 after 0 usecs > >> calling bdi_class_init+0x0/0x40 @ 1 > >> > >> config attached. > > > > Thanks. AFAICT, it's this one: > > > > 1816 void sock_init_data(struct socket *sock, struct sock *sk) > > 1817 { > > ... > > 1835 sock_set_flag(sk, SOCK_ZAPPED); > > Are you sure it is not the 16 bit padding in 'struct sock', after 'type' field ? > > struct socket { > socket_state state; > short type; > // here, a 16 bits hole > unsigned long flags; > > the warning is strange since I suspect it happens here : > > if (sock) { > <<>> sk->sk_type = sock->type; // here, kmemcheck warning while reading sock->type > sk->sk_sleep = &sock->wait; > sock->sk = sk; > > and sock->type is a 16 bit field, correctly initialized (with value = 2) > (Yes the hole, right after, is not initialized) > > WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f5c38304) > 0100000002000000000000000000000000000000ad4eaddeffffffffffffffff > i i i i i i u u i i i i i i i i i i i i i i i i i i i i i i i i
if so then we could perhaps annotate that by initializing it to zero on kmemcheck only. (or initialize it unconditionally if possible - that's generally the cleanest, 16-bit accesses arent cheap on all platforms)
Ingo
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