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 E11641CEAB2; Sun, 24 Nov 2024 12:47:28 +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=1732452449; cv=none; b=bqwhcn1lapQM3qzqQPJMDCvLymztF7uZ8XwJqDFsdOItex/uebWlGrPvklnYx1vNxNbkszPkrz0E6iFQd6RuqHUcjIeIAZG9oXepi1r4iKscfZbuvAx1bF0VSedVadA8o3IV+ZDSvc5aafx2rpuifnfRV97wg0Gak697XrPS1Ak= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732452449; c=relaxed/simple; bh=a8538FsydKZeS6CG2poVFhOrpVNi/7MNKMPk6Qx9Fj0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=iQ+elm5/EqAfEakSKHXnZ1xA2GUvFPrJvi/wZ89SKxvNRUFJpovW6+6zgmhIPnjrAhJJTqCaRHKCUpyp8VwsNa4qzH8EI/V52pOF6SHDm8fYA6JRuLPvaFnkqN2+/T9kqa5slQvcFV9L58eYxDzbm1qxRvUIJ50Si8L+be7hk9o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=riAEK0m1; 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="riAEK0m1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D846C4CED9; Sun, 24 Nov 2024 12:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732452448; bh=a8538FsydKZeS6CG2poVFhOrpVNi/7MNKMPk6Qx9Fj0=; h=From:To:Cc:Subject:Date:From; b=riAEK0m1mkH/QkPWhnDnJr6Bw/p0cMtByP9V/+6bjC9eMfFyGAeeOqFj0YEqHQYUC dd0Rca06iosHIDqxFlbxnFZLvS6Vyhfq5IyPt3macmIBJV6W1JzZtLEna5roxPG2Qo pkYvMP7xoVhMlTts50nXtYAUx1qB5mU2ah5hXAF5u02+vfAHPqHczCIiSV1FQ/fC6/ 7Tn37JZ+WUkMHaiXcUOpoh/QL8wT9xgziSqIqJRm7EB0GWDgfpblostlN260PiEb+n 2OtXgIICV0+G8mjO+VosTlNk2wTyW8GWtmWjhu4QAoVrcwg3cNBXDKKZh+10pO1NAa ijtZwz96YenFA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Oleg Nesterov , Peter Zijlstra , Sasha Levin , mhiramat@kernel.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH AUTOSEL 5.15 1/2] uprobes: sanitiize xol_free_insn_slot() Date: Sun, 24 Nov 2024 07:47:23 -0500 Message-ID: <20241124124726.3338494-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.173 Content-Transfer-Encoding: 8bit From: Oleg Nesterov [ Upstream commit c7b4133c48445dde789ed30b19ccb0448c7593f7 ] 1. Clear utask->xol_vaddr unconditionally, even if this addr is not valid, xol_free_insn_slot() should never return with utask->xol_vaddr != NULL. 2. Add a comment to explain why do we need to validate slot_addr. 3. Simplify the validation above. We can simply check offset < PAGE_SIZE, unsigned underflows are fine, it should work if slot_addr < area->vaddr. 4. Kill the unnecessary "slot_nr >= UINSNS_PER_PAGE" check, slot_nr must be valid if offset < PAGE_SIZE. The next patches will cleanup this function even more. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240929144235.GA9471@redhat.com Signed-off-by: Sasha Levin --- kernel/events/uprobes.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index b37a6bde8a915..a0f846b2ac1ea 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1633,8 +1633,8 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) static void xol_free_insn_slot(struct task_struct *tsk) { struct xol_area *area; - unsigned long vma_end; unsigned long slot_addr; + unsigned long offset; if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) return; @@ -1643,24 +1643,21 @@ static void xol_free_insn_slot(struct task_struct *tsk) if (unlikely(!slot_addr)) return; + tsk->utask->xol_vaddr = 0; area = tsk->mm->uprobes_state.xol_area; - vma_end = area->vaddr + PAGE_SIZE; - if (area->vaddr <= slot_addr && slot_addr < vma_end) { - unsigned long offset; - int slot_nr; - - offset = slot_addr - area->vaddr; - slot_nr = offset / UPROBE_XOL_SLOT_BYTES; - if (slot_nr >= UINSNS_PER_PAGE) - return; + offset = slot_addr - area->vaddr; + /* + * slot_addr must fit into [area->vaddr, area->vaddr + PAGE_SIZE). + * This check can only fail if the "[uprobes]" vma was mremap'ed. + */ + if (offset < PAGE_SIZE) { + int slot_nr = offset / UPROBE_XOL_SLOT_BYTES; clear_bit(slot_nr, area->bitmap); atomic_dec(&area->slot_count); smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ if (waitqueue_active(&area->wq)) wake_up(&area->wq); - - tsk->utask->xol_vaddr = 0; } } -- 2.43.0