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 C503D1BBBEE; Sun, 24 Nov 2024 12:46:26 +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=1732452386; cv=none; b=gEh9CZpSDEXlG4qFzlUk1ai9CbJtnfwGCSwMHjj6J452pOFqUXqCjwIVWUIclHFlcOKrCyNHJJSQ3tsjW4nxHXj2/P82coW0S6l+YSMRyvvPA0kVubMoT6Z3qiHN7RwlDsmy5jrt29h7sHRd44AH7cF7o+VAz2BSBy9C40TGtF8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732452386; c=relaxed/simple; bh=sA9g5Eu8ASeFls4iVRs/Rqrj0T7ijfTMFjnwdbEAiSM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=r76KKXn5NHZFCQspKAf5/HNLDD/LIpp5BwnjNyr178JKEmyZD11+vVWtU/zK8pLdDAQN7EP/OMjCy2cGCAGZSObETt5uHiud0vH8s6Wm85xnu4RBpFFEesEqk0ATOK3y4qMPJHSe2LY3XxceH+LdOllY94wJE7nCEG0FGsm6r6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rifF6LT6; 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="rifF6LT6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1FEC9C4CECC; Sun, 24 Nov 2024 12:46:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732452386; bh=sA9g5Eu8ASeFls4iVRs/Rqrj0T7ijfTMFjnwdbEAiSM=; h=From:To:Cc:Subject:Date:From; b=rifF6LT63qSJKtKTKu5fQiJ+/8fOXmx6BFYqzai65XPBTzRrnvMRhfSmpZnLEk+mJ b4IYWHp7Rd2EQrMrFO43/bASN0toEqrD5/2fyjMiza57E0W1QrcHxZvJEOulDyzy7N p4Rji9lPkbx5/jl6g1StrnmkOSb4KWgF7A0c2ES4ijJWtHaTf3zd9XMPXEVvrzyC2k s/ZJe/Wy876Pz5TK/D3t/S+DORFtMOE6OGYyfGEf/Ri1kQs7hMr5IgiQNYGFkmLCXd 3BSnTT/QB3dsaXTdjc6avUvD6My588oAiUCglXHWrrT1KhR23mqAzDvCPm3w73mhng tbmSuq2OsTV0Q== 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 6.12 1/5] uprobes: sanitiize xol_free_insn_slot() Date: Sun, 24 Nov 2024 07:46:13 -0500 Message-ID: <20241124124623.3337983-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-trace-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 6.12.1 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 4b52cb2ae6d62..cc605df73d72f 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1683,8 +1683,8 @@ 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; @@ -1693,24 +1693,21 @@ 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