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[185.56.211.78]) by smtp.gmail.com with ESMTPSA id k2sm1545519lfm.13.2020.11.01.13.27.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Nov 2020 13:27:40 -0800 (PST) Date: Sun, 1 Nov 2020 22:27:38 +0100 From: =?utf-8?B?UGF3ZcWC?= Jasiak To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, jack@suse.cz Subject: PROBLEM: fanotify_mark EFAULT on x86 Message-ID: <20201101212738.GA16924@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="x+6KMIRAuhnl3hBn" Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --x+6KMIRAuhnl3hBn Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable I am trying to run examples from man fanotify.7 but fanotify_mark always fail with errno =3D EFAULT. fanotify_mark declaration is SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, __u64, mask, int, dfd, const char __user *, pathname) When=20 fanotify_mark(4, FAN_MARK_ADD | FAN_MARK_ONLYDIR, FAN_CREATE | FAN_ONDIR, AT_FDCWD, 0xdeadc0de) is called on kernel side I can see in do_syscall_32_irqs_on that CPU context is bx =3D 0x4 =3D 4 cx =3D 0x9 =3D FAN_MARK_ADD | FAN_MARK_ONLYDIR, dx =3D 0x40000100 =3D FAN_CREATE | FAN_ONDIR si =3D 0x0 di =3D 0xffffff9c =3D AT_FDCWD bp =3D 0xdeadc0de ax =3D 0xffffffda orix_ax =3D 0x153 I am not sure if it is ok because third argument is uint64_t so if I understand correctly mask should be divided into two registers (dx and si). But in fanotify_mark we get fanotify_fd =3D 4 =3D bx flags =3D 0x9 =3D cx mask =3D 0x40000100 =3D dx dfd =3D 0 =3D si pathname =3D 0xffffff9c =3D di I believe that correct order is fanotify_fd =3D 4 =3D bx flags =3D 0x9 =3D cx mask =3D 0x40000100 =3D (si << 32) | dx dfd =3D 0xffffff9c =3D di pathname =3D 0xdeadc0de =3D bp I think that we should call COMPAT version of fanotify_mark here COMPAT_SYSCALL_DEFINE6(fanotify_mark, int, fanotify_fd, unsigned int, flags, __u32, mask0, __u32, mask1, int, dfd, const char __user *, pathname) or something wrong is with 64-bits arguments. I am running Linux 5.9.2 i686 on Pentium III (Coppermine). For tests I am using Debian sid on qemu with 5.9.2 and default kernel =66rom repositories. Everything works fine on 5.5 and 5.4. --=20 Pawe=C5=82 Jasiak --x+6KMIRAuhnl3hBn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEENIqkLxDcCMlLMdi0FzfmQudzVTgFAl+fKEYACgkQFzfmQudz VTiEgQ//aiyjua4unpQBiXkKTTNgv1ICPmPSvR1YO26NKiF5oIW/EZDf1aKOdd4h zCUR+rt74wtxbKlwIwMYokS9PJveh1H8WgWie+hmGCxR8shPZhKR3YthtuzTR6TO t6PR2IWUA6S7gPxdh0aWrq6cQMTLJEQ5fO8W9lCBpwE5FAZH4phki5a5/K1a9YGN uT4o++BUha1txqsnd7syKpT3o0buY2/92U2lQJQJt3Vyu1FRjif1qXIr2cyzaWPe EmbQP9+9I8k92JycO6trj4Yd9NbtUZk+/215p9255r6yuQ4RLSkBRehfBRzPTEbp FvKEeVQZX0tYM1B3WO+A5xqaGHKFItQOmsBJ8Bc7052ljZe4jk2GdaFc4EShUMd/ 5QJpH8O+GCxbeZX5vY7ieftyRBxWIcWVPaevngpv6OV7sY3NY3ZmbIfcbbHoZkBL PzFfvEsfEqabaL9qHV0+ZQowNxO+RFtwEwPlXCdeYBNibP16disvzzLZ81tHf8xj 6sJKUwS/aAQ3vLnk1/2b04/QVCu81wvi8GgOd/tQxHWHimjvl0i6ukC8iQlO94bU jsZPuVtVFYbREwimgqGtI9R5vd37gGeS9Bd0o6Kyz0+PdYlo33K/GoV987djeG2P HAPCyn5SDD7lV24x+O3/3WdxwSnsZyGqw3kXuqFPMU5OvUmHgwc= =9KzB -----END PGP SIGNATURE----- --x+6KMIRAuhnl3hBn--