Revision 732256b9335f8456623bb772d86c2a24e3cafca2 authored by Erik Hugne on 07 January 2014, 20:51:36 UTC, committed by David S. Miller on 07 January 2014, 21:15:24 UTC
When we pull a received packet from a link's 'deferred packets' queue for processing, its 'next' pointer is not cleared, and still refers to the next packet in that queue, if any. This is incorrect, but caused no harm before commit 40ba3cdf542a469aaa9083fa041656e59b109b90 ("tipc: message reassembly using fragment chain") was introduced. After that commit, it may sometimes lead to the following oops: general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: tipc CPU: 4 PID: 0 Comm: swapper/4 Tainted: G W 3.13.0-rc2+ #6 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 task: ffff880017af4880 ti: ffff880017aee000 task.ti: ffff880017aee000 RIP: 0010:[<ffffffff81710694>] [<ffffffff81710694>] skb_try_coalesce+0x44/0x3d0 RSP: 0018:ffff880016603a78 EFLAGS: 00010212 RAX: 6b6b6b6bd6d6d6d6 RBX: ffff880013106ac0 RCX: ffff880016603ad0 RDX: ffff880016603ad7 RSI: ffff88001223ed00 RDI: ffff880013106ac0 RBP: ffff880016603ab8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88001223ed00 R13: ffff880016603ad0 R14: 000000000000058c R15: ffff880012297650 FS: 0000000000000000(0000) GS:ffff880016600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 000000000805b000 CR3: 0000000011f5d000 CR4: 00000000000006e0 Stack: ffff880016603a88 ffffffff810a38ed ffff880016603aa8 ffff88001223ed00 0000000000000001 ffff880012297648 ffff880016603b68 ffff880012297650 ffff880016603b08 ffffffffa0006c51 ffff880016603b08 00ffffffa00005fc Call Trace: <IRQ> [<ffffffff810a38ed>] ? trace_hardirqs_on+0xd/0x10 [<ffffffffa0006c51>] tipc_link_recv_fragment+0xd1/0x1b0 [tipc] [<ffffffffa0007214>] tipc_recv_msg+0x4e4/0x920 [tipc] [<ffffffffa00016f0>] ? tipc_l2_rcv_msg+0x40/0x250 [tipc] [<ffffffffa000177c>] tipc_l2_rcv_msg+0xcc/0x250 [tipc] [<ffffffffa00016f0>] ? tipc_l2_rcv_msg+0x40/0x250 [tipc] [<ffffffff8171e65b>] __netif_receive_skb_core+0x80b/0xd00 [<ffffffff8171df94>] ? __netif_receive_skb_core+0x144/0xd00 [<ffffffff8171eb76>] __netif_receive_skb+0x26/0x70 [<ffffffff8171ed6d>] netif_receive_skb+0x2d/0x200 [<ffffffff8171fe70>] napi_gro_receive+0xb0/0x130 [<ffffffff815647c2>] e1000_clean_rx_irq+0x2c2/0x530 [<ffffffff81565986>] e1000_clean+0x266/0x9c0 [<ffffffff81985f7b>] ? notifier_call_chain+0x2b/0x160 [<ffffffff8171f971>] net_rx_action+0x141/0x310 [<ffffffff81051c1b>] __do_softirq+0xeb/0x480 [<ffffffff819817bb>] ? _raw_spin_unlock+0x2b/0x40 [<ffffffff810b8c42>] ? handle_fasteoi_irq+0x72/0x100 [<ffffffff81052346>] irq_exit+0x96/0xc0 [<ffffffff8198cbc3>] do_IRQ+0x63/0xe0 [<ffffffff81981def>] common_interrupt+0x6f/0x6f <EOI> This happens when the last fragment of a message has passed through the the receiving link's 'deferred packets' queue, and at least one other packet was added to that queue while it was there. After the fragment chain with the complete message has been successfully delivered to the receiving socket, it is released. Since 'next' pointer of the last fragment in the released chain now is non-NULL, we get the crash shown above. We fix this by clearing the 'next' pointer of all received packets, including those being pulled from the 'deferred' queue, before they undergo any further processing. Fixes: 40ba3cdf542a4 ("tipc: message reassembly using fragment chain") Signed-off-by: Erik Hugne <erik.hugne@ericsson.com> Reported-by: Ying Xue <ying.xue@windriver.com> Reviewed-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 657e5d1
freezer.c
/*
* kernel/freezer.c - Function to freeze a process
*
* Originally from kernel/power/process.c
*/
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
/* total number of freezing conditions in effect */
atomic_t system_freezing_cnt = ATOMIC_INIT(0);
EXPORT_SYMBOL(system_freezing_cnt);
/* indicate whether PM freezing is in effect, protected by pm_mutex */
bool pm_freezing;
bool pm_nosig_freezing;
/*
* Temporary export for the deadlock workaround in ata_scsi_hotplug().
* Remove once the hack becomes unnecessary.
*/
EXPORT_SYMBOL_GPL(pm_freezing);
/* protects freezing and frozen transitions */
static DEFINE_SPINLOCK(freezer_lock);
/**
* freezing_slow_path - slow path for testing whether a task needs to be frozen
* @p: task to be tested
*
* This function is called by freezing() if system_freezing_cnt isn't zero
* and tests whether @p needs to enter and stay in frozen state. Can be
* called under any context. The freezers are responsible for ensuring the
* target tasks see the updated state.
*/
bool freezing_slow_path(struct task_struct *p)
{
if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
return false;
if (pm_nosig_freezing || cgroup_freezing(p))
return true;
if (pm_freezing && !(p->flags & PF_KTHREAD))
return true;
return false;
}
EXPORT_SYMBOL(freezing_slow_path);
/* Refrigerator is place where frozen processes are stored :-). */
bool __refrigerator(bool check_kthr_stop)
{
/* Hmm, should we be allowed to suspend when there are realtime
processes around? */
bool was_frozen = false;
long save = current->state;
pr_debug("%s entered refrigerator\n", current->comm);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
spin_lock_irq(&freezer_lock);
current->flags |= PF_FROZEN;
if (!freezing(current) ||
(check_kthr_stop && kthread_should_stop()))
current->flags &= ~PF_FROZEN;
spin_unlock_irq(&freezer_lock);
if (!(current->flags & PF_FROZEN))
break;
was_frozen = true;
schedule();
}
pr_debug("%s left refrigerator\n", current->comm);
/*
* Restore saved task state before returning. The mb'd version
* needs to be used; otherwise, it might silently break
* synchronization which depends on ordered task state change.
*/
set_current_state(save);
return was_frozen;
}
EXPORT_SYMBOL(__refrigerator);
static void fake_signal_wake_up(struct task_struct *p)
{
unsigned long flags;
if (lock_task_sighand(p, &flags)) {
signal_wake_up(p, 0);
unlock_task_sighand(p, &flags);
}
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
*
* If @p is freezing, the freeze request is sent either by sending a fake
* signal (if it's not a kernel thread) or waking it up (if it's a kernel
* thread).
*
* RETURNS:
* %false, if @p is not freezing or already frozen; %true, otherwise
*/
bool freeze_task(struct task_struct *p)
{
unsigned long flags;
/*
* This check can race with freezer_do_not_count, but worst case that
* will result in an extra wakeup being sent to the task. It does not
* race with freezer_count(), the barriers in freezer_count() and
* freezer_should_skip() ensure that either freezer_count() sees
* freezing == true in try_to_freeze() and freezes, or
* freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task
* normally.
*/
if (freezer_should_skip(p))
return false;
spin_lock_irqsave(&freezer_lock, flags);
if (!freezing(p) || frozen(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
if (!(p->flags & PF_KTHREAD))
fake_signal_wake_up(p);
else
wake_up_state(p, TASK_INTERRUPTIBLE);
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}
void __thaw_task(struct task_struct *p)
{
unsigned long flags;
/*
* Clear freezing and kick @p if FROZEN. Clearing is guaranteed to
* be visible to @p as waking up implies wmb. Waking up inside
* freezer_lock also prevents wakeups from leaking outside
* refrigerator.
*/
spin_lock_irqsave(&freezer_lock, flags);
if (frozen(p))
wake_up_process(p);
spin_unlock_irqrestore(&freezer_lock, flags);
}
/**
* set_freezable - make %current freezable
*
* Mark %current freezable and enter refrigerator if necessary.
*/
bool set_freezable(void)
{
might_sleep();
/*
* Modify flags while holding freezer_lock. This ensures the
* freezer notices that we aren't frozen yet or the freezing
* condition is visible to try_to_freeze() below.
*/
spin_lock_irq(&freezer_lock);
current->flags &= ~PF_NOFREEZE;
spin_unlock_irq(&freezer_lock);
return try_to_freeze();
}
EXPORT_SYMBOL(set_freezable);
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