From: Al Viro Date: Tue, 31 Jan 2023 04:51:40 +0000 (-0500) Subject: nios2: fix livelock in uaccess X-Git-Tag: v6.6.17~5353^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e902e508c5b280488c62f119a05ad88f9f7eb1cb;p=platform%2Fkernel%2Flinux-rpi.git nios2: fix livelock in uaccess nios2 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 --- diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c index edaca0a..ca64ecc 100644 --- a/arch/nios2/mm/fault.c +++ b/arch/nios2/mm/fault.c @@ -136,8 +136,11 @@ good_area: */ fault = handle_mm_fault(vma, address, flags, regs); - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; return; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED)