[PATCH bpf 1/2] libbpf: fix null dereference in xsk_socket__delete

[Magnus Karlsson]

From: Magnus Karlsson <magnus.karls...@intel.com>

Fix a possible null pointer dereference in xsk_socket__delete that
will occur if a null pointer is fed into the function.

Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices")
Reported-by: Andrii Nakryiko <andrii.nakry...@gmail.com>
Signed-off-by: Magnus Karlsson <magnus.karls...@intel.com>
---
 tools/lib/bpf/xsk.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index e3c98c0..504b7a8 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -891,13 +891,14 @@ int xsk_umem__delete(struct xsk_umem *umem)
 void xsk_socket__delete(struct xsk_socket *xsk)
 {
        size_t desc_sz = sizeof(struct xdp_desc);
-       struct xsk_ctx *ctx = xsk->ctx;
        struct xdp_mmap_offsets off;
+       struct xsk_ctx *ctx;
        int err;
 
        if (!xsk)
                return;
 
+       ctx = xsk->ctx;
        if (ctx->prog_fd != -1) {
                xsk_delete_bpf_maps(xsk);
                close(ctx->prog_fd);
-- 
2.7.4