From: Al Viro Date: Tue, 31 Jan 2023 04:53:52 +0000 (-0500) Subject: parisc: fix livelock in uaccess X-Git-Tag: v6.6.7~3334^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=15261678a8c2ff093ffedad730b1646d34a1716a;p=platform%2Fkernel%2Flinux-starfive.git parisc: fix livelock in uaccess parisc 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. Tested-by: Helge Deller Signed-off-by: Al Viro --- diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c index 869204e..6941fdb 100644 --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -308,8 +308,13 @@ 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)) { + msg = "Page fault: fault signal on kernel memory"; + goto no_context; + } return; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED)