aio: prevent double free in ioctx_alloc

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@oracle.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/aio.c b/fs/aio.c
index fff5db091e7e6cf0a5bbedae7ef4b8e7fac5d2aa..f4103b3634c64d3205ca0d430170571c78d51863 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -661,7 +661,6 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 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);