From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: [PATCH 09/10] riscv: fix livelock in uaccess Date: Tue, 31 Jan 2023 20:06:48 +0000 Message-ID: References: Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=nvc6EOOE6Kc37iQ5tEQ7l2xOJqqEJfVCbXPLSTxaEF4=; b=wdY4q/NUsSzoOzzSH9JWxFXi7s Tk1MepTXqcFNQuqsv6PLGLDlWg/ho5Hq7LbS/6/Ozd57SshWTeDBArvFWXDhGFh2BhNX8dBI4LgkO LpJmKqpkO4x5vY1+b9CcqUE0aGIpoyS5qStg8iBjcK+HypQyzzYiPNvF/dOM89WyZgG3dUo1oR8AB ONYs1wDgkd19QVLeBTvry12xY2pe789ERsnyEmEuQrns462tlSiqhjy4E15CVoyugsuWlzfNMig0b a6a88eJ+8ZtJ/kyRgEu6wVtRz1ghz6pXOq3cyUYQcf7ksmGIi6rbK4dPwUT0N6fTylQGUN8noABNX qOw7Ui/A==; Content-Disposition: inline In-Reply-To: Sender: Al Viro List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arch@vger.kernel.org Cc: linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, Michal Simek , Dinh Nguyen , openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org, Linus Torvalds riscv equivalent of 26178ec11ef3 "x86: mm: consolidate VM_FAULT_RETRY handling" If e.g. get_user() triggers a page fault and a fatal signal is caught, we might end up with handle_mm_fault() returning VM_FAULT_RETRY and not doing anything to page tables. In such case we must *not* return to the faulting insn - that would repeat the entire thing without making any progress; what we need instead is to treat that as failed (user) memory access. Signed-off-by: Al Viro --- arch/riscv/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c index d86f7cebd4a7..c91d85349d39 100644 --- a/arch/riscv/mm/fault.c +++ b/arch/riscv/mm/fault.c @@ -324,8 +324,11 @@ asmlinkage void do_page_fault(struct pt_regs *regs) * signal first. We do not need to release the mmap_lock because it * would already be released in __lock_page_or_retry in mm/filemap.c. */ - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + no_context(regs, addr); return; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED) -- 2.30.2