From: Al Viro Date: Tue, 31 Jan 2023 04:48:54 +0000 (-0500) Subject: m68k: fix livelock in uaccess X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bd75497a77ccae9a5e1b0f1a3fa8283d67b21f4c;p=linux.git m68k: fix livelock in uaccess 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. Tested-by: Finn Thain Tested-by: Geert Uytterhoeven Acked-by: Geert Uytterhoeven Signed-off-by: Al Viro --- diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index 4d2837eb3e2a3..228128e45c673 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -138,8 +138,11 @@ good_area: 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)