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)
