From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B870248BD31 for ; Tue, 14 Jul 2026 14:51:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784040685; cv=none; b=dz8M30B3KlmIWE9wnn49jU+vsRz49HVlm9E+Z5ToJZW6R44dU/CH25xhmk/aYA158cvRaSGgE0J4pruwFbvjFz5aM12Eea6opj2MwfhniQIwbd2zBnLfRlneBXpJZiH5mVnJk2sJDzmKdoNjzPoOExjTzH0OAaUyVlQmNYteVPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784040685; c=relaxed/simple; bh=p4qopVJ4TWRtF+rqajbHDVjyVplUbwAjO19/QK5SHUE=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=rjKvT7tLYbAUQVj5XBIiP75bsetD3hj6cg1jfYF5Fyh9lLt8UUd1Uj54M9STt/s2Eb2MrgwUa48e5IJb4SlmV+vX4Yj6Naqm3H7XPp/hfoqu+dV3+Y6zqb0XT/P1C0a66PAeGkMFSIF+i9c3XBiPtZC07s40xub8489u7yUnLc4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=G2cVKfoM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="G2cVKfoM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A1181F000E9; Tue, 14 Jul 2026 14:51:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784040675; bh=cx964i4uujchALv/viHDT+0H9+W+nH5ciuMRu34IEEY=; h=Subject:To:Cc:From:Date; b=G2cVKfoMD1vrhOjEavhJTy7RtNKsft2Ds4Io9/xS5hFKJYxpHqBeKarByK8LJOzcv +dBEVWO19x216J38WKMzp76j/IEuHIu4pBM/J2tTjhHko/QS/HyoDgg6I59IF1RfBj oLLRCFQfEpX2zqvifnJHGpOGJjvQr0wd2XPCFRQo= Subject: FAILED: patch "[PATCH] proc: protect ptrace_may_access() with exec_update_lock (part" failed to apply to 5.15-stable tree To: jannh@google.com,brauner@kernel.org Cc: From: Date: Tue, 14 Jul 2026 16:50:45 +0200 Message-ID: <2026071445-ridden-persuader-5fac@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6650527444dadc63d84aa939d14ecba4fadb2f69 # git commit -s git send-email --to '' --in-reply-to '2026071445-ridden-persuader-5fac@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6650527444dadc63d84aa939d14ecba4fadb2f69 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Mon, 18 May 2026 18:35:15 +0200 Subject: [PATCH] proc: protect ptrace_may_access() with exec_update_lock (part 1) Fix the easy cases where procfs currently calls ptrace_may_access() without exec_update_lock protection, where the fix is to simply add the extra lock or use mm_access(): - do_task_stat(): grab exec_update_lock - proc_pid_wchan(): grab exec_update_lock - proc_map_files_lookup(): use mm_access() instead of get_task_mm() - proc_map_files_readdir(): use mm_access() instead of get_task_mm() - proc_ns_get_link(): grab exec_update_lock - proc_ns_readlink(): grab exec_update_lock Fixes: f83ce3e6b02d ("proc: avoid information leaks to non-privileged processes") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Link: https://patch.msgid.link/20260518-procfs-lockfix-part1-v1-1-5c3d20e0ac33@google.com Signed-off-by: Christian Brauner (Amutable) diff --git a/fs/proc/array.c b/fs/proc/array.c index 90fb0c6b5f99..479ea8cb4ef4 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -482,6 +482,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, unsigned long flags; int exit_code = task->exit_code; struct signal_struct *sig = task->signal; + int ret; + + ret = down_read_killable(&task->signal->exec_update_lock); + if (ret) + return ret; state = *get_task_state(task); vsize = eip = esp = 0; @@ -657,6 +662,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, seq_puts(m, " 0"); seq_putc(m, '\n'); + up_read(&task->signal->exec_update_lock); if (mm) mmput(mm); return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index d9acfa89c894..cc99d953a0a3 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -423,18 +423,24 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns, { unsigned long wchan; char symname[KSYM_NAME_LEN]; + int err; + err = down_read_killable(&task->signal->exec_update_lock); + if (err) + return err; if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) goto print0; wchan = get_wchan(task); if (wchan && !lookup_symbol_name(wchan, symname)) { seq_puts(m, symname); + up_read(&task->signal->exec_update_lock); return 0; } print0: seq_putc(m, '0'); + up_read(&task->signal->exec_update_lock); return 0; } #endif /* CONFIG_KALLSYMS */ @@ -2360,17 +2366,15 @@ static struct dentry *proc_map_files_lookup(struct inode *dir, if (!task) goto out; - result = ERR_PTR(-EACCES); - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; - result = ERR_PTR(-ENOENT); if (dname_to_vma_addr(dentry, &vm_start, &vm_end)) goto out_put_task; - mm = get_task_mm(task); - if (!mm) + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); + if (IS_ERR(mm)) { + result = ERR_CAST(mm); goto out_put_task; + } result = ERR_PTR(-EINTR); if (mmap_read_lock_killable(mm)) @@ -2420,24 +2424,23 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) if (!task) goto out; - ret = -EACCES; - if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) - goto out_put_task; - ret = 0; if (!dir_emit_dots(file, ctx)) goto out_put_task; - mm = get_task_mm(task); - if (!mm) - goto out_put_task; - - ret = mmap_read_lock_killable(mm); - if (ret) { - mmput(mm); + mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); + if (IS_ERR(mm)) { + ret = PTR_ERR(mm); + /* if the task has no mm, the directory should just be empty */ + if (ret == -ESRCH) + ret = 0; goto out_put_task; } + ret = mmap_read_lock_killable(mm); + if (ret) + goto out_put_mm; + nr_files = 0; /* @@ -2462,8 +2465,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) if (!p) { ret = -ENOMEM; mmap_read_unlock(mm); - mmput(mm); - goto out_put_task; + goto out_put_mm; } p->start = vma->vm_start; @@ -2471,7 +2473,6 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) p->mode = vma->vm_file->f_mode; } mmap_read_unlock(mm); - mmput(mm); for (i = 0; i < nr_files; i++) { char buf[4 * sizeof(long) + 2]; /* max: %lx-%lx\0 */ @@ -2488,6 +2489,8 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) ctx->pos++; } +out_put_mm: + mmput(mm); out_put_task: put_task_struct(task); out: diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 39f4169f669f..2f46f1396744 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -55,6 +55,10 @@ static const char *proc_ns_get_link(struct dentry *dentry, if (!task) return ERR_PTR(-EACCES); + error = down_read_killable(&task->signal->exec_update_lock); + if (error) + goto out_put_task; + if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) goto out; @@ -64,6 +68,8 @@ static const char *proc_ns_get_link(struct dentry *dentry, error = nd_jump_link(&ns_path); out: + up_read(&task->signal->exec_update_lock); +out_put_task: put_task_struct(task); return ERR_PTR(error); } @@ -80,11 +86,17 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl if (!task) return res; + res = down_read_killable(&task->signal->exec_update_lock); + if (res) + goto out_put_task; + if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) { res = ns_get_name(name, sizeof(name), task, ns_ops); if (res >= 0) res = readlink_copy(buffer, buflen, name, strlen(name)); } + up_read(&task->signal->exec_update_lock); +out_put_task: put_task_struct(task); return res; }