From nobody Wed Oct 8 16:40:14 2025 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 94DC42ED152; Thu, 26 Jun 2025 17:13:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750957988; cv=none; b=YG2467vBnotLREBJLdzprkEc4K3AgL9pKQKCKSuXeEJ7Y6FmlNZ0O6ekJI/2hgpWeGvbzfPCxgCOtwgTVoAJdWuueyIYtnDdMoNtOKW7yvMOCfPUQAnOEtw2AyNffzNzAR7LhNDTr8Y6Agehq/oGKy01gIYTThkxrAokeTKYbyc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750957988; c=relaxed/simple; bh=CUtwUKXDz4DkNMp5YBD/tJDHmFUCeORwEy4IRtoJ3G8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=RcySRtwdqCRpEj64CRiFOftXcePF4yIa3A/WjtzZPe9TnMm8DId2ELwY0Kl0WGRzgSmnQTeuj4PFF90hMyfr5GeKAFTb1M725pvW+XNrkA5rOBq+weM2jCnResVFCTDCrs9cDFYc+e6k3GlPvJtCTmJpP0OroigU/za/2jCWJpY= 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=OY5Yq3Yv; arc=none smtp.client-ip=213.97.179.56 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="OY5Yq3Yv" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Cc:To:In-Reply-To:References:Message-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: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=Yf/WUr3lC/ecExHg82fOS+TmR2AOfqu+uEiB301mkDI=; b=OY5Yq3YvcnkztpfBbZL/6wXXpC WkuVdVPov3ok8JORX+pGJp255DoYSRC81zMCWBHcQ7FJoj+RZJZfZdj9Thp4GlOmbbNf8w2w4A9dd cC0Jj0Lp019kupc/HDSzZocIoP3VYJBP2t5Uo1oi6zGu8uhGcOfcjSA+ePwDW/cmz+FcsIWrf9FKl DxXD7RpMFkM0uu9aQi5aX8pLR6DjgMX6+lbR8oI9Mzt7g7PwItkjGXi8JzXn+rCK66ctbL4T2Ycoy IK/PT96RVWDRRDMPNJh2aw3md3mpFO8PbURaugvr3jo2KDlInN6+L1AkVyS3tWX3alNkqCWyWAsy9 P32EUVCA==; Received: from [191.204.192.64] (helo=[192.168.15.100]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1uUq9o-009491-B1; Thu, 26 Jun 2025 19:13:04 +0200 From: =?utf-8?q?Andr=C3=A9_Almeida?= Date: Thu, 26 Jun 2025 14:11:27 -0300 Subject: [PATCH v5 3/7] futex: Use explicit sizes for compat_exit_robust_list 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 Message-Id: <20250626-tonyk-robust_futex-v5-3-179194dbde8f@igalia.com> References: <20250626-tonyk-robust_futex-v5-0-179194dbde8f@igalia.com> In-Reply-To: <20250626-tonyk-robust_futex-v5-0-179194dbde8f@igalia.com> To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , Shuah Khan , Arnd Bergmann , Sebastian Andrzej Siewior , Waiman Long Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-api@vger.kernel.org, kernel-dev@igalia.com, =?utf-8?q?Andr=C3=A9_Almeida?= X-Mailer: b4 0.14.2 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 | 10 ++++++++++ include/linux/sched.h | 2 +- kernel/futex/core.c | 48 ++++++++++++++++++++++++++++++++-------------= --- kernel/futex/syscalls.c | 4 ++-- 5 files changed, 46 insertions(+), 30 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 56cebaff0c910fda853a0e2b3d6d0517e55f8b38..968a9135ff486cf9c8be2a18b80= cd4c46e890236 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 b37193653e6b5d7d562ac08f93d4ee41eb8e72a2..c5b6976909c7d51360e1831e017= f4d1544c258fa 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -55,6 +55,16 @@ union futex_key { =20 #define FUTEX_KEY_INIT (union futex_key) { .both =3D { .ptr =3D 0ULL } } =20 +struct robust_list32 { + u32 next; +}; + +struct robust_list_head32 { + struct robust_list32 list; + s32 futex_offset; + u32 list_op_pending; +}; + #ifdef CONFIG_FUTEX enum { FUTEX_STATE_OK, diff --git a/include/linux/sched.h b/include/linux/sched.h index 4f78a64beb52c425e46c66427b2f608ba30b3d99..b0f64029d53e8b2ab56f24f7705= 4aa7645a185c5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1333,7 +1333,7 @@ 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 90d53fb0ee9e1563c355ef0499df441367e1a46c..f0ac4b897ddbb667fa85daf5853= cb47c749d512d 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1144,15 +1144,16 @@ static inline int fetch_robust_entry(struct robust_= list __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) { - struct robust_list_head __user *head =3D curr->robust_list; struct robust_list __user *entry, *next_entry, *pending; unsigned int limit =3D ROBUST_LIST_LIMIT, pi, pip; unsigned int next_pi; @@ -1211,8 +1212,15 @@ static void exit_robust_list(struct task_struct *cur= r) curr, pip, HANDLE_DEATH_PENDING); } } +#else +static void exit_robust_list64(struct task_struct *curr, + struct robust_list_head __user *head) +{ + pr_warn("32bit kernel should not allow ROBUST_LIST_64BIT"); +} +#endif =20 -#ifdef CONFIG_COMPAT +#if defined(CONFIG_COMPAT) || !defined(CONFIG_64BIT) static void __user *futex_uaddr(struct robust_list __user *entry, compat_long_t futex_offset) { @@ -1226,13 +1234,13 @@ 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; @@ -1244,21 +1252,21 @@ compat_fetch_robust_entry(compat_uptr_t *uentry, st= ruct 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 robust_list_head32 __user *head) { - struct compat_robust_list_head __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: @@ -1269,7 +1277,7 @@ static void compat_exit_robust_list(struct task_struc= t *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 @@ -1279,8 +1287,8 @@ static void compat_exit_robust_list(struct task_struc= t *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: @@ -1406,14 +1414,22 @@ 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); tsk->robust_list =3D NULL; } +#else + if (unlikely(tsk->robust_list)) { + exit_robust_list32(tsk, + (struct robust_list_head32 __user *) tsk->robust_list); + 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); tsk->compat_robust_list =3D NULL; } #endif diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 4b6da9116aa6c33db9796e3055ce0c90b02d7b91..dba193dfd216cc929c8f4d979aa= 2bcd99237e2d8 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 2.49.0