netdev - [PATCH bpf-next V1] selftests/bpf: fix unmap bug in prog_tests/xdp

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Message-ID: <167527517464.938135.13750760520577765269.stgit@firesoul>
Date:   Wed, 01 Feb 2023 19:12:54 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     bpf@...r.kernel.org, Stanislav Fomichev <sdf@...gle.com>
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
        martin.lau@...nel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org,
        yhs@...com, john.fastabend@...il.com, dsahern@...il.com,
        willemb@...gle.com, void@...ifault.com, kuba@...nel.org,
        xdp-hints@...-project.net
Subject: [PATCH bpf-next V1] selftests/bpf: fix unmap bug in
 prog_tests/xdp_metadata.c

The function close_xsk() unmap via munmap() the wrong memory pointer.

The call xsk_umem__delete(xsk->umem) have already freed xsk->umem.
Thus the call to munmap(xsk->umem, UMEM_SIZE) will have unpredictable
behavior that can lead to Segmentation fault elsewhere, as man page
explain subsequent references to these pages will generate SIGSEGV.

Fixes: e2a46d54d7a1 ("selftests/bpf: Verify xdp_metadata xdp->af_xdp path")
Reported-by: Martin KaFai Lau <martin.lau@...nel.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 .../selftests/bpf/prog_tests/xdp_metadata.c        |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
index e033d48288c0..241909d71c7e 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
@@ -121,7 +121,7 @@ static void close_xsk(struct xsk *xsk)
 		xsk_umem__delete(xsk->umem);
 	if (xsk->socket)
 		xsk_socket__delete(xsk->socket);
-	munmap(xsk->umem, UMEM_SIZE);
+	munmap(xsk->umem_area, UMEM_SIZE);
 }
 
 static void ip_csum(struct iphdr *iph)