Guenter, On 1/03/23 04:22, Guenter Roeck wrote:
On Tue, Jan 31, 2023 at 08:06:27PM +0000, Al Viro wrote: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. Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> --- arch/parisc/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c index 869204e97ec9..bb30ff6a3e19 100644 --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -308,8 +308,11 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,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;0-day rightfully complains that this leaves 'msg' uninitialized. arch/parisc/mm/fault.c:427 do_page_fault() error: uninitialized symbol 'msg' Guenter
What happens if you initialize msg to "Page fault: no context" right at the start of do_page_fault (and drop the assignment a few lines down as that's now redundant)?
(Wondering if the zero page access on parisc could cause a trip right back into do_page_fault, ad infinitum...)
Cheers, Michael
return; + }/* The fault is fully completed (including releasing mmap lock) */if (fault & VM_FAULT_COMPLETED)
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