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 13C451F3D56; Fri, 16 Jan 2026 18:35:11 +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=1768588512; cv=none; b=T8QsjoLGGjYnFcoUmcV4AE07kAUnv522Vpb+LFsexU6oz126NY5DJDCAmwY1kyqIxno4pBinX+b9+QRRAm8Jgnv+9vs/7GDJpkJxU8VV/OTifb5TqMcO3un5azGsWxT1NTWlj1Nn8Pfw9nMBQMVI5MyUtp3PDQOr4wqboJCGPao= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768588512; c=relaxed/simple; bh=BduuunRIrRrpujEbFLJpjG0uQ7tb8xG+8DWRUUOslXA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=BWFmosK51xCzYF3/3V+4SxpOGYkorauf3rZF9jsKBDWB5+pLvUyyZ4S6TC88t3fXa9/4TDUCBUmxWwwrAfto1dWxdga86lf1ltcab55JR+PiCj8G1COrR5ENynweyCHi8aeR3VgJp2LT0NWlbRNMoqbaaZSGMaCQsExz2jqhIa4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=emxY1FlW; 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="emxY1FlW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01976C116C6; Fri, 16 Jan 2026 18:35:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768588511; bh=BduuunRIrRrpujEbFLJpjG0uQ7tb8xG+8DWRUUOslXA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=emxY1FlW1DxsyLskm3AGtm7FzUj78fR2ZN8KpGnc66+xAzV63wB1nyjekfe+PiBNE 7yAee4wFrNjv0ojKwr0YaAVkFH0go9YBRSkaj7CcGTZGXj4fF7Uo2ClV9dMWklvMqU kKjxHETuiFTdW/XZfWpQ3yXl1sQnmV7OZyGlm8jktrYiXEoSB5bSFqXIE3x3QdNpHA AISUsO9aBifsi+qnZQxjHq0aK5lHHfghnZHeLiBxm3jB6TKDRDdZ+whrHdKDfsFKpg +bQH9FSyCh453uIl+LnQGhZAyPay6zzZtzdW/XvbjzRKTim4u3zG2cDK0NdQ80i66p U4iS9so8rN8pA== Message-ID: Subject: Re: [PATCH] nfsd: fix NULL pointer dereference in check_export() From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 16 Jan 2026 13:35:09 -0500 In-Reply-To: <20260116-nfsd-fixes-v1-1-019689b72747@kernel.org> References: <20260116-nfsd-fixes-v1-1-019689b72747@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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path that has no export operations. > Check that the export_ops are set and just return -EINVAL if not. >=20 > Signed-off-by: Jeff Layton > --- > Triggering this required a rather pathological export table (I just > exported "/"). Given that, I'm on the fence as to whether we want to > send this to stable. > --- > fs/nfsd/export.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) >=20 > diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c > index 2a1499f2ad196a6033787260881e451146283bdc..4187c109d84985d33a69e1929= 1edbf2b27b257d8 100644 > --- a/fs/nfsd/export.c > +++ b/fs/nfsd/export.c > @@ -405,6 +405,7 @@ static struct svc_export *svc_export_lookup(struct sv= c_export *); > static int check_export(const struct path *path, int *flags, unsigned ch= ar *uuid) > { > struct inode *inode =3D d_inode(path->dentry); > + struct export_operations *export_op =3D inode->i_sb->s_export_op; > =20 > /* > * We currently export only dirs, regular files, and (for v4 > @@ -422,14 +423,20 @@ static int check_export(const struct path *path, in= t *flags, unsigned char *uuid > if (*flags & NFSEXP_V4ROOT) > *flags |=3D NFSEXP_READONLY; > =20 > - /* There are two requirements on a filesystem to be exportable. > - * 1: We must be able to identify the filesystem from a number. > + /* There are four requirements on a filesystem to be exportable: > + * 1: It must define sb->s_export_op > + * 2: We must be able to identify the filesystem from a number. > * either a device number (so FS_REQUIRES_DEV needed) > * or an FSID number (so NFSEXP_FSID or ->uuid is needed). > - * 2: We must be able to find an inode from a filehandle. > + * 3: We must be able to find an inode from a filehandle. > * This means that s_export_op must be set. > - * 3: We must not currently be on an idmapped mount. > + * 4: We must not currently be on an idmapped mount. > */ > + if (!export_op) { > + dprintk("%s: fs doesn't define export_operations!\n", __func__); > + return -EINVAL; > + } > + > if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) && > !(*flags & NFSEXP_FSID) && > uuid =3D=3D NULL) { > @@ -437,7 +444,7 @@ static int check_export(const struct path *path, int = *flags, unsigned char *uuid > return -EINVAL; > } > =20 > - if (!exportfs_can_decode_fh(inode->i_sb->s_export_op)) { > + if (!exportfs_can_decode_fh(export_op)) { Hrm, actually exportfs_can_decode_fh() already checks this. You can disregard this patch.=20 --=20 Jeff Layton