From: Magnus Karlsson magnus.karlsson@intel.com
[ Upstream commit e6762c8bcf982821935a2b1cb33cf8335d0eefae ]
All the setup code in AF_XDP is protected by a mutex with the exception of the mmap code that cannot use it. To make sure that a process banging on the mmap call at the same time as another process is setting up the socket, smp_wmb() calls were added in the umem registration code and the queue creation code, so that the published structures that xsk_mmap needs would be consistent. However, the corresponding smp_rmb() calls were not added to the xsk_mmap code. This patch adds these calls.
Fixes: 37b076933a8e3 ("xsk: add missing write- and data-dependency barrier") Fixes: c0c77d8fb787c ("xsk: add user memory registration support sockopt") Signed-off-by: Magnus Karlsson magnus.karlsson@intel.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/xdp/xsk.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index ff15207036dc..547fc4554b22 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -661,6 +661,8 @@ static int xsk_mmap(struct file *file, struct socket *sock, if (!umem) return -EINVAL;
+ /* Matches the smp_wmb() in XDP_UMEM_REG */ + smp_rmb(); if (offset == XDP_UMEM_PGOFF_FILL_RING) q = READ_ONCE(umem->fq); else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING) @@ -670,6 +672,8 @@ static int xsk_mmap(struct file *file, struct socket *sock, if (!q) return -EINVAL;
+ /* Matches the smp_wmb() in xsk_init_queue */ + smp_rmb(); qpg = virt_to_head_page(q->ring); if (size > (PAGE_SIZE << compound_order(qpg))) return -EINVAL;