[PATCH 3.12 79/83] aio: prevent double free in ioctx_alloc

[Greg Kroah-Hartman]

3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sasha Levin <sasha.levin@xxxxxxxxxx>

commit d558023207e008a4476a3b7bb8706b2a2bf5d84f upstream.

ioctx_alloc() calls aio_setup_ring() to allocate a ring. If aio_setup_ring()
fails to do so it would call aio_free_ring() before returning, but
ioctx_alloc() would call aio_free_ring() again causing a double free of
the ring.

This is easily reproducible from userspace.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/aio.c |    1 -
 1 file changed, 1 deletion(-)

--- a/fs/aio.c
+++ b/fs/aio.c
@@ -661,7 +661,6 @@ static struct kioctx *ioctx_alloc(unsign
 err_cleanup:
 	aio_nr_sub(ctx->max_reqs);
 err:
-	aio_free_ring(ctx);
 	free_percpu(ctx->cpu);
 	free_percpu(ctx->reqs.pcpu_count);
 	free_percpu(ctx->users.pcpu_count);


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