Commit ff8c1474 authored Mar 14, 2012 by Xiaotian Feng Committed by Jens Axboe Mar 14, 2012

block: fix ioc leak in put_io_context



When put_io_context is called, if ioc->icq_list is empty and refcount
is 1, kernel will not free the ioc.

This is caught by following kmemleak:

unreferenced object 0xffff880036349fe0 (size 216):
  comm "sh", pid 2137, jiffies 4294931140 (age 290579.412s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    01 00 01 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
  backtrace:
    [<ffffffff8169f926>] kmemleak_alloc+0x26/0x50
    [<ffffffff81195a9c>] kmem_cache_alloc_node+0x1cc/0x2a0
    [<ffffffff81356b67>] create_io_context_slowpath+0x27/0x130
    [<ffffffff81356d2b>] get_task_io_context+0xbb/0xf0
    [<ffffffff81055f0e>] copy_process+0x188e/0x18b0
    [<ffffffff8105609b>] do_fork+0x11b/0x420
    [<ffffffff810247f8>] sys_clone+0x28/0x30
    [<ffffffff816d3373>] stub_clone+0x13/0x20
    [<ffffffffffffffff>] 0xffffffffffffffff

ioc should be freed if ioc->icq_list is empty.
Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent ea5f4db8

block/blk-ioc.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -130,6 +130,7 @@ static void ioc_release_fn(struct work_struct *work)
		void put_io_context(struct io_context *ioc)
		{
		unsigned long flags;
		bool free_ioc = false;

		if (ioc == NULL)
		return;
		@@ -144,8 +145,13 @@ void put_io_context(struct io_context *ioc)
		spin_lock_irqsave(&ioc->lock, flags);
		if (!hlist_empty(&ioc->icq_list))
		schedule_work(&ioc->release_work);
		else
		free_ioc = true;
		spin_unlock_irqrestore(&ioc->lock, flags);
		}

		if (free_ioc)
		kmem_cache_free(iocontext_cachep, ioc);
		}
		EXPORT_SYMBOL(put_io_context);

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