From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A17193BF2E4; Thu, 15 Jan 2026 16:59:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768496347; cv=none; b=TFy6BSkiEaEOH4BHSYTZ7EeIGBlF3lgwR91TLQ0OtYGAE0JcJu1MVEcx4KYVgK3hXys8tukGW4x2ZlL7QMGl1aV185XimvltGmXk6ft0LRT5Av4TpU0GZi382DoT7SAWhXNrscAaJOeyOocKPILBEOuilIRWxLTsy9ZeCog6VVc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768496347; c=relaxed/simple; bh=eYHt2miYXTEaLqNKxRIUx0tMgmIcFIOKKskEbZzBOes=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=k/3kUP9Qw6KyQlXX0Ex//DamhaysMZbjKoQV2BjbMn0ghgggm3ntNc89RBrqagXCrWbOa0NcvgX/ZOncYB3XW5WK3mrwrE+z53td4d68PYqH1c1545s4fA1IXNzB1sSMU+iZojnMuURJf85yxHMtlQU0Kjf/hzW+Vx5HSU9ia+Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hZuhxZG8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hZuhxZG8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDB7CC116D0; Thu, 15 Jan 2026 16:59:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768496347; bh=eYHt2miYXTEaLqNKxRIUx0tMgmIcFIOKKskEbZzBOes=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hZuhxZG8RbW2FFgqiCTr6fI6CISokvcsiV8Phw9nkwJ9+BwlCS4aUcehHdH4RaAqq spYvq7jNtnSe2qPWM8lz6GRkVj+W4tJtLxUZCV5260M/SOcSz9f2pVreJXKmVYoDz/ BntxlvCPoOCeXKqZs1c3V1ctjeOJp2IzmOuF4Wbs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com, Tetsuo Handa , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.18 164/181] bpf: Fix reference count leak in bpf_prog_test_run_xdp() Date: Thu, 15 Jan 2026 17:48:21 +0100 Message-ID: <20260115164208.236103302@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164202.305475649@linuxfoundation.org> References: <20260115164202.305475649@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa [ Upstream commit ec69daabe45256f98ac86c651b8ad1b2574489a7 ] 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 Signed-off-by: Sasha Levin --- net/bpf/test_run.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 59620fdd5cfda..6b04f47301c1e 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1300,13 +1300,13 @@ 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++]; @@ -1318,7 +1318,7 @@ 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; @@ -1333,6 +1333,7 @@ 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. -- 2.51.0