From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: [PATCH 04/10] m68k: fix livelock in uaccess Date: Tue, 31 Jan 2023 20:04:56 +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=6IKigZkqFBsGpbA9ajZ2Iw9VszpR27B7CG3/bEQJDxY=; b=eqmvDT91wCunq2V0AGR+ix+Vs+ YV3cRNHbq+Oy47qp3ylEH4Hx8wSoOkaEB/q4RsfIimm+3zp2sK8JZ5/AkCaGprUFjL3LaVBMyP2wb ctSr4iPJXbxHiVykZr70RsmiAkRaZ3BbjqgAuai0uhpcmiS5vwLi62m3UYSrqalvn/nZqUk37rCq4 hoDGKkp6jhvk9o+s3m9EWdmlljeMqELxaKTo/d3KRlTgwkcfslaVe+qAu9wCEu9cF6JTtjDYu7z4P gffgyZDBbqPaD23gHSwlTUZ72eJwvSErKw+PO7gny0NokmaAPqBpro/zvO2bxOQO4z0uezIuymel6 sGcFpM0Q==; 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 m68k 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/m68k/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index 4d2837eb3e2a..228128e45c67 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -138,8 +138,11 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, fault = handle_mm_fault(vma, address, flags, regs); pr_debug("handle_mm_fault returns %x\n", fault); - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; return 0; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED) -- 2.30.2