Commit f8567a38 authored Jun 24, 2014 by Benjamin LaHaise

aio: fix aio request leak when events are reaped by userspace



The aio cleanups and optimizations by kmo that were merged into the 3.10
tree added a regression for userspace event reaping.  Specifically, the
reference counts are not decremented if the event is reaped in userspace,
leading to the application being unable to submit further aio requests.
This patch applies to 3.12+.  A separate backport is required for 3.10/3.11.
This issue was uncovered as part of CVE-2014-0206.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: stable@vger.kernel.org
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>

parent 8b8f5d97

fs/aio.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1021,6 +1021,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)

		/* everything turned out well, dispose of the aiocb. */
		kiocb_free(iocb);
		put_reqs_available(ctx, 1);

		/*
		* We have to order our ring_info tail store above and test
		@@ -1100,8 +1101,6 @@ static long aio_read_events_ring(struct kioctx *ctx,
		flush_dcache_page(ctx->ring_pages[0]);

		pr_debug("%li h%u t%u\n", ret, head, tail);

		put_reqs_available(ctx, ret);
		out:
		mutex_unlock(&ctx->ring_lock);

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