From: Tetsuo Handa Date: Thu, 8 Jan 2026 12:36:48 +0000 (+0900) Subject: bpf: Fix reference count leak in bpf_prog_test_run_xdp() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ec69daabe45256f98ac86c651b8ad1b2574489a7;p=thirdparty%2Flinux.git bpf: Fix reference count leak in bpf_prog_test_run_xdp() syzbot is reporting unregister_netdevice: waiting for sit0 to become free. Usage count = 2 problem. A debug printk() patch found that a refcount is obtained at xdp_convert_md_to_buff() from bpf_prog_test_run_xdp(). According to commit ec94670fcb3b ("bpf: Support specifying ingress via xdp_md context in BPF_PROG_TEST_RUN"), the refcount obtained by xdp_convert_md_to_buff() will be released by xdp_convert_buff_to_md(). Therefore, we can consider that the error handling path introduced by commit 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()") forgot to call xdp_convert_buff_to_md(). Reported-by: syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84 Fixes: 1c1949982524 ("bpf: introduce frags support to bpf_prog_test_run_xdp()") Signed-off-by: Tetsuo Handa Reviewed-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/af090e53-9d9b-4412-8acb-957733b3975c@I-love.SAKURA.ne.jp Signed-off-by: Alexei Starovoitov --- diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index e6c0ad204b92..26cfcfdc45eb 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1363,13 +1363,13 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, if (sinfo->nr_frags == MAX_SKB_FRAGS) { ret = -ENOMEM; - goto out; + goto out_put_dev; } page = alloc_page(GFP_KERNEL); if (!page) { ret = -ENOMEM; - goto out; + goto out_put_dev; } frag = &sinfo->frags[sinfo->nr_frags++]; @@ -1381,7 +1381,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, if (copy_from_user(page_address(page), data_in + size, data_len)) { ret = -EFAULT; - goto out; + goto out_put_dev; } sinfo->xdp_frags_size += data_len; size += data_len; @@ -1396,6 +1396,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, ret = bpf_test_run_xdp_live(prog, &xdp, repeat, batch_size, &duration); else ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true); +out_put_dev: /* We convert the xdp_buff back to an xdp_md before checking the return * code so the reference count of any held netdevice will be decremented * even if the test run failed.