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xsk: avoid store-tearing when assigning umem 

The umem member of struct xdp_sock is read outside of the control
mutex, in the mmap implementation, and needs a WRITE_ONCE to avoid
potential store-tearing.

Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Fixes: 423f38329d ("xsk: add umem fill queue support and mmap")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Björn Töpel 2019-09-04 13:49:11 +02:00 committed by Daniel Borkmann
parent 94a997637c
commit 9764f4b301
1 changed files with 2 additions and 2 deletions
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4
net/xdp/xsk.c
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@ -644,7 +644,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
}
xdp_get_umem(umem_xs->umem);
xs->umem = umem_xs->umem;
WRITE_ONCE(xs->umem, umem_xs->umem);
sockfd_put(sock);
} else if (!xs->umem || !xdp_umem_validate_queues(xs->umem)) {
err = -EINVAL;
@ -751,7 +751,7 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
/* Make sure umem is ready before it can be seen by others */
smp_wmb();
xs->umem = umem;
WRITE_ONCE(xs->umem, umem);
mutex_unlock(&xs->mutex);
return 0;
}