From nobody Thu Dec 18 09:49:01 2025 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 8C8061FA24A; Tue, 17 Dec 2024 17:50:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734457838; cv=none; b=S2H7C7jJvZmkubM6aBGZHEtPTt1H0yMXfhmQ7lthrXBLuNjxq7PYZOzMPsLonRxfgLjTggo6jN4ZVPyWBKF+WQWcVG2M40QagCX3N1CmzdoFNl4P5ZJ7Av3LMpM9BMyrQWAQnzleR2NF9WMgiQXU0TXy5x6CtoUICM7qlmToxu0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734457838; c=relaxed/simple; bh=jzrqXHPRri0P6rFE5fZgk5GvG91c3FyjXKbzeyhtRyU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=F80ShJciYlNy+8ecOjuRyVTtbGw/u9CxI9xZqtb0QGR0tQMWO6JLFhszvlPLiuu4Rz4QnZEKu18KBZyCBKd+gW0vKDp6OIidBgz5odyJePgjN1rHc7ntZWf5jgdssYGXZ+Il2dLfGV584bdvmZ+RvTHy9yzy64Z/Vk6jecgVWaw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=BAhRt2z4; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="BAhRt2z4" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=en/1Agr+y3QLCPkhOQuxhb7wode+cza9tVICK+e8Xb8=; b=BAhRt2z4hzCjeoJcWY4a719C+D xRe0U8atujMGBepkqRCdYs8R6dnWcgev9wEBfpTgR9/Hgot6oeypWo1jSS2r9vvg7ojYPfob9W1RH eNFRO90Cw5NLtMBgJhriGa82FUhb6WiKgieiUF6Rzg/L79wXd7FMWQZpE3+r01Uv98CvVKU5c6WID mZfiWExzI0XXRgxaJ+9icYwUOvwmzGuDOw1zmD+3bxN2Q6qWzLpJBuYTlnPqze2lhN7qnCT0iATY8 cHFh3q3Daa95gnZ6Ubp5FDQSHj4lMUco/WyG9nZqljL2xb03TekgjQGs6SLNVWcDscryw8m9XcUPU awlKEVXA==; Received: from [179.193.1.214] (helo=localhost.localdomain) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1tNbhy-004TVV-KR; Tue, 17 Dec 2024 18:50:11 +0100 From: =?UTF-8?q?Andr=C3=A9=20Almeida?= To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , Arnd Bergmann , sonicadvance1@gmail.com Cc: linux-kernel@vger.kernel.org, kernel-dev@igalia.com, linux-api@vger.kernel.org, Nathan Chancellor , Vinicius Peixoto , =?UTF-8?q?Andr=C3=A9=20Almeida?= Subject: [PATCH v3 1/3] futex: Use explicit sizes for compat_exit_robust_list Date: Tue, 17 Dec 2024 14:49:56 -0300 Message-ID: <20241217174958.477692-2-andrealmeid@igalia.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241217174958.477692-1-andrealmeid@igalia.com> References: <20241217174958.477692-1-andrealmeid@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable There are two functions for handling robust lists during the task exit: exit_robust_list() and compat_exit_robust_list(). The first one handles either 64bit or 32bit lists, depending if it's a 64bit or 32bit kernel. The compat_exit_robust_list() only exists in 64bit kernels that supports 32bit syscalls, and handles 32bit lists. For the new syscall set_robust_list2(), 64bit kernels need to be able to handle 32bit lists despite having or not support for 32bit syscalls, so make compat_exit_robust_list() exist regardless of compat_ config. Also, use explicitly sizing, otherwise in a 32bit kernel both exit_robust_list() and compat_exit_robust_list() would be the exactly same function, with none of them dealing with 64bit robust lists. Signed-off-by: Andr=C3=A9 Almeida --- include/linux/compat.h | 12 +---------- include/linux/futex.h | 11 +++++++++++ include/linux/sched.h | 2 +- kernel/futex/core.c | 44 ++++++++++++++++++++++++++--------------- kernel/futex/syscalls.c | 4 ++-- 5 files changed, 43 insertions(+), 30 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 56cebaff0c91..968a9135ff48 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -385,16 +385,6 @@ struct compat_ifconf { compat_caddr_t ifcbuf; }; =20 -struct compat_robust_list { - compat_uptr_t next; -}; - -struct compat_robust_list_head { - struct compat_robust_list list; - compat_long_t futex_offset; - compat_uptr_t list_op_pending; -}; - #ifdef CONFIG_COMPAT_OLD_SIGACTION struct compat_old_sigaction { compat_uptr_t sa_handler; @@ -672,7 +662,7 @@ asmlinkage long compat_sys_waitid(int, compat_pid_t, struct compat_siginfo __user *, int, struct compat_rusage __user *); asmlinkage long -compat_sys_set_robust_list(struct compat_robust_list_head __user *head, +compat_sys_set_robust_list(struct robust_list_head32 __user *head, compat_size_t len); asmlinkage long compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, diff --git a/include/linux/futex.h b/include/linux/futex.h index b70df27d7e85..8217b5ebdd9c 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -53,6 +53,17 @@ union futex_key { #define FUTEX_KEY_INIT (union futex_key) { .both =3D { .ptr =3D 0ULL } } =20 #ifdef CONFIG_FUTEX + +struct robust_list32 { + u32 next; +}; + +struct robust_list_head32 { + struct robust_list32 list; + s32 futex_offset; + u32 list_op_pending; +}; + enum { FUTEX_STATE_OK, FUTEX_STATE_EXITING, diff --git a/include/linux/sched.h b/include/linux/sched.h index 66b311fbd5d6..da573c16e93e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1292,7 +1292,7 @@ struct task_struct { #ifdef CONFIG_FUTEX struct robust_list_head __user *robust_list; #ifdef CONFIG_COMPAT - struct compat_robust_list_head __user *compat_robust_list; + struct robust_list_head32 __user *compat_robust_list; #endif struct list_head pi_state_list; struct futex_pi_state *pi_state_cache; diff --git a/kernel/futex/core.c b/kernel/futex/core.c index ebdd76b4ecbb..cc2d0f00cd6b 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -768,13 +768,14 @@ static inline int fetch_robust_entry(struct robust_li= st __user **entry, return 0; } =20 +#ifdef CONFIG_64BIT /* * Walk curr->robust_list (very carefully, it's a userspace list!) * and mark any locks found there dead, and notify any waiters. * * We silently return on any sign of list-walking problem. */ -static void exit_robust_list(struct task_struct *curr) +static void exit_robust_list64(struct task_struct *curr) { struct robust_list_head __user *head =3D curr->robust_list; struct robust_list __user *entry, *next_entry, *pending; @@ -835,8 +836,13 @@ static void exit_robust_list(struct task_struct *curr) curr, pip, HANDLE_DEATH_PENDING); } } +#else +static void exit_robust_list64(struct task_struct *curr) +{ + pr_warn("32bit kernel should not allow ROBUST_LIST_64BIT"); +} +#endif =20 -#ifdef CONFIG_COMPAT static void __user *futex_uaddr(struct robust_list __user *entry, compat_long_t futex_offset) { @@ -850,13 +856,13 @@ static void __user *futex_uaddr(struct robust_list __= user *entry, * Fetch a robust-list pointer. Bit 0 signals PI futexes: */ static inline int -compat_fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user= **entry, - compat_uptr_t __user *head, unsigned int *pi) +fetch_robust_entry32(u32 *uentry, struct robust_list __user **entry, + u32 __user *head, unsigned int *pi) { if (get_user(*uentry, head)) return -EFAULT; =20 - *entry =3D compat_ptr((*uentry) & ~1); + *entry =3D (void __user *)(unsigned long)((*uentry) & ~1); *pi =3D (unsigned int)(*uentry) & 1; =20 return 0; @@ -868,21 +874,21 @@ compat_fetch_robust_entry(compat_uptr_t *uentry, stru= ct robust_list __user **ent * * We silently return on any sign of list-walking problem. */ -static void compat_exit_robust_list(struct task_struct *curr) +static void exit_robust_list32(struct task_struct *curr) { - struct compat_robust_list_head __user *head =3D curr->compat_robust_list; + struct robust_list_head32 __user *head =3D curr->compat_robust_list; struct robust_list __user *entry, *next_entry, *pending; unsigned int limit =3D ROBUST_LIST_LIMIT, pi, pip; unsigned int next_pi; - compat_uptr_t uentry, next_uentry, upending; - compat_long_t futex_offset; + u32 uentry, next_uentry, upending; + s32 futex_offset; int rc; =20 /* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): */ - if (compat_fetch_robust_entry(&uentry, &entry, &head->list.next, &pi)) + if (fetch_robust_entry32((u32 *)&uentry, &entry, (u32 *)&head->list.next,= &pi)) return; /* * Fetch the relative futex offset: @@ -893,7 +899,7 @@ static void compat_exit_robust_list(struct task_struct = *curr) * Fetch any possibly pending lock-add first, and handle it * if it exists: */ - if (compat_fetch_robust_entry(&upending, &pending, + if (fetch_robust_entry32(&upending, &pending, &head->list_op_pending, &pip)) return; =20 @@ -903,8 +909,8 @@ static void compat_exit_robust_list(struct task_struct = *curr) * Fetch the next entry in the list before calling * handle_futex_death: */ - rc =3D compat_fetch_robust_entry(&next_uentry, &next_entry, - (compat_uptr_t __user *)&entry->next, &next_pi); + rc =3D fetch_robust_entry32(&next_uentry, &next_entry, + (u32 __user *)&entry->next, &next_pi); /* * A pending lock might already be on the list, so * dont process it twice: @@ -935,7 +941,6 @@ static void compat_exit_robust_list(struct task_struct = *curr) handle_futex_death(uaddr, curr, pip, HANDLE_DEATH_PENDING); } } -#endif =20 #ifdef CONFIG_FUTEX_PI =20 @@ -1018,14 +1023,21 @@ static inline void exit_pi_state_list(struct task_s= truct *curr) { } =20 static void futex_cleanup(struct task_struct *tsk) { +#ifdef CONFIG_64BIT if (unlikely(tsk->robust_list)) { - exit_robust_list(tsk); + exit_robust_list64(tsk); tsk->robust_list =3D NULL; } +#else + if (unlikely(tsk->robust_list)) { + exit_robust_list32(tsk); + tsk->robust_list =3D NULL; + } +#endif =20 #ifdef CONFIG_COMPAT if (unlikely(tsk->compat_robust_list)) { - compat_exit_robust_list(tsk); + exit_robust_list32(tsk); tsk->compat_robust_list =3D NULL; } #endif diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 4b6da9116aa6..dba193dfd216 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -440,7 +440,7 @@ SYSCALL_DEFINE4(futex_requeue, =20 #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE2(set_robust_list, - struct compat_robust_list_head __user *, head, + struct robust_list_head32 __user *, head, compat_size_t, len) { if (unlikely(len !=3D sizeof(*head))) @@ -455,7 +455,7 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, compat_uptr_t __user *, head_ptr, compat_size_t __user *, len_ptr) { - struct compat_robust_list_head __user *head; + struct robust_list_head32 __user *head; unsigned long ret; struct task_struct *p; =20 --=20 2.47.1