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 DD9EB55887; Mon, 27 Jan 2025 14:51:01 +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=1737989462; cv=none; b=kKCugr+jcj4hQFnsQfEKQzFWTtO3Mqpo4YH9esjakgEA2wKP19pglNg3GaYyI9sIuGiRl2RYwgM3Kx7vaGy+kpfbeInjUcoD7ZFWw7ThdCZPHCw11MhWiVG0U/+HNB536/Hd0CPmntLz+T8LpwoEE/wuxOMxv/8+VcbgDluKP+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737989462; c=relaxed/simple; bh=iNoxg0PLRlCXZNFpo0ojPHSZVpecRkRiMv7DxJtLwjU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=KqcV5OKkjRBCScDZzqUKSYge2mbzfqFUe+5Ytg7bPpQeR8NBZdDYy8/CbO5rWVOh9R6n+U9IHCKycRSzG+Z3pZdBKAMgoraUWPIHOjO/TFe9LvRMPnw5Ff8BbeEbi5rs2aYqU3NRCejsoBJYDkEoKPxqsftdsXVWtgpgX3kbqPU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=skL/OWKe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="skL/OWKe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 436DFC4CEE1; Mon, 27 Jan 2025 14:51:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737989461; bh=iNoxg0PLRlCXZNFpo0ojPHSZVpecRkRiMv7DxJtLwjU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=skL/OWKel8NwKhWAxd2Bu7Wk9yoq+YIoVfxiX9DdZoOX7bUTuPPXKgOLuYx+t98/I 8yaOzDoLdPbRS5Jh2z0tH8f+WWUvgZS46Yr+JKra6pgc+4hnC26xatPdl02FwvyJnf qXU1xjg6ZCfV9BFXTvns584g1KKMbzILSYcbF/C5LraBqPsSMB9T+HLXewRGdqflja aOAeuDoJX8OP883moSPxmkk7S4VT2n9lYvyM7nGUfKW57/v/JBlVHVC2DPd+2VMB1p /Jzf2/Cb8jK0fFZq8BupUWsfutSDIjbMiHUj3ck+aO2kGaRw3dLOosuVRnGyLTyiYI rxNa+ZAINb0vA== Message-ID: <34922f8d915c7d10f04d65fd44a50ba6d9b1615b.camel@kernel.org> Subject: Re: [PATCH v2] nfsd: clear acl_access/acl_default after releasing them From: Jeff Layton To: Li Lingfeng , chuck.lever@oracle.com, neilb@suse.de, okorniev@redhat.com, kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com, Trond.Myklebust@netapp.com, rick.macklem@gmail.com, zhangjian496@huawei.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com Date: Mon, 27 Jan 2025 09:50:59 -0500 In-Reply-To: <20250126094722.738358-1-lilingfeng3@huawei.com> References: <20250126094722.738358-1-lilingfeng3@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; 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text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sun, 2025-01-26 at 17:47 +0800, Li Lingfeng wrote: > If getting acl_default fails, acl_access and acl_default will be released > simultaneously. However, acl_access will still retain a pointer pointing > to the released posix_acl, which will trigger a WARNING in > nfs3svc_release_getacl like this: >=20 > ------------[ cut here ]------------ > refcount_t: underflow; use-after-free. > WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28 > refcount_warn_saturate+0xb5/0x170 > Modules linked in: > CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted > 6.12.0-rc6-00079-g04ae226af01f-dirty #8 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > 1.16.1-2.fc37 04/01/2014 > RIP: 0010:refcount_warn_saturate+0xb5/0x170 > Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75 > e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb > cd 0f b6 1d 8a3 > RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde > RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380 > RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56 > R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001 > R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0 > FS: 0000000000000000(0000) GS:ffff88871ed00000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > ? refcount_warn_saturate+0xb5/0x170 > ? __warn+0xa5/0x140 > ? refcount_warn_saturate+0xb5/0x170 > ? report_bug+0x1b1/0x1e0 > ? handle_bug+0x53/0xa0 > ? exc_invalid_op+0x17/0x40 > ? asm_exc_invalid_op+0x1a/0x20 > ? tick_nohz_tick_stopped+0x1e/0x40 > ? refcount_warn_saturate+0xb5/0x170 > ? refcount_warn_saturate+0xb5/0x170 > nfs3svc_release_getacl+0xc9/0xe0 > svc_process_common+0x5db/0xb60 > ? __pfx_svc_process_common+0x10/0x10 > ? __rcu_read_unlock+0x69/0xa0 > ? __pfx_nfsd_dispatch+0x10/0x10 > ? svc_xprt_received+0xa1/0x120 > ? xdr_init_decode+0x11d/0x190 > svc_process+0x2a7/0x330 > svc_handle_xprt+0x69d/0x940 > svc_recv+0x180/0x2d0 > nfsd+0x168/0x200 > ? __pfx_nfsd+0x10/0x10 > kthread+0x1a2/0x1e0 > ? kthread+0xf4/0x1e0 > ? __pfx_kthread+0x10/0x10 > ret_from_fork+0x34/0x60 > ? __pfx_kthread+0x10/0x10 > ret_from_fork_asm+0x1a/0x30 > > Kernel panic - not syncing: kernel: panic_on_warn set ... >=20 > Clear acl_access/acl_default after posix_acl_release is called to prevent > UAF from being triggered. >=20 > Fixes: a257cdd0e217 ("[PATCH] NFSD: Add server support for NFSv3 ACLs.") > Link: https://lore.kernel.org/all/20241107014705.2509463-1-lilingfeng@hua= weicloud.com/ > Signed-off-by: Li Lingfeng > --- > Changes in v2: > - Clear acl_access/acl_default after releasing them, instead of > modifying the logic for setting them. > - Clear acl_access/acl_default in nfs2acl.c. > --- > fs/nfsd/nfs2acl.c | 2 ++ > fs/nfsd/nfs3acl.c | 2 ++ > 2 files changed, 4 insertions(+) >=20 > diff --git a/fs/nfsd/nfs2acl.c b/fs/nfsd/nfs2acl.c > index 4e3be7201b1c..5fb202acb0fd 100644 > --- a/fs/nfsd/nfs2acl.c > +++ b/fs/nfsd/nfs2acl.c > @@ -84,6 +84,8 @@ static __be32 nfsacld_proc_getacl(struct svc_rqst *rqst= p) > fail: > posix_acl_release(resp->acl_access); > posix_acl_release(resp->acl_default); > + resp->acl_access =3D NULL; > + resp->acl_default =3D NULL; > goto out; > } > =20 > diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c > index 5e34e98db969..7b5433bd3019 100644 > --- a/fs/nfsd/nfs3acl.c > +++ b/fs/nfsd/nfs3acl.c > @@ -76,6 +76,8 @@ static __be32 nfsd3_proc_getacl(struct svc_rqst *rqstp) > fail: > posix_acl_release(resp->acl_access); > posix_acl_release(resp->acl_default); > + resp->acl_access =3D NULL; > + resp->acl_default =3D NULL; > goto out; > } > =20 Nice catch. Reviewed-by: Jeff Layton