From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Date: Tue, 31 Jan 2023 20:06:48 +0000 Subject: [PATCH 09/10] riscv: fix livelock in uaccess Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 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