From: Al Viro Date: Tue, 31 Jan 2023 04:55:52 +0000 (-0500) Subject: riscv: fix livelock in uaccess X-Git-Tag: v6.6.7~3334^2~8 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d835eb3a57de50d16dd4a6b53f95dbc2bfa8ef48;p=platform%2Fkernel%2Flinux-starfive.git riscv: fix livelock in uaccess 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. Tested-by: Björn Töpel Tested-by: Geert Uytterhoeven Signed-off-by: Al Viro --- diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c index d86f7ce..c91d853 100644 --- a/arch/riscv/mm/fault.c +++ b/arch/riscv/mm/fault.c @@ -324,8 +324,11 @@ good_area: * 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)