-----Original Message-----
From: Al Viro <viro@xxxxxxxxxxxxxxxx> On Behalf Of Al Viro
Sent: Tuesday, January 31, 2023 2:04 PM
To: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-alpha@xxxxxxxxxxxxxxx; linux-ia64@xxxxxxxxxxxxxxx; linux-
hexagon@xxxxxxxxxxxxxxx; linux-m68k@xxxxxxxxxxxxxxxxxxxx; Michal Simek
<monstr@xxxxxxxxx>; Dinh Nguyen <dinguyen@xxxxxxxxxx>;
openrisc@xxxxxxxxxxxxxxxxxxxx; linux-parisc@xxxxxxxxxxxxxxx; linux-
riscv@xxxxxxxxxxxxxxxxxxx; sparclinux@xxxxxxxxxxxxxxx; Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx>
Subject: [PATCH 02/10] hexagon: fix livelock in uaccess
WARNING: This email originated from outside of Qualcomm. Please be wary of
any links or attachments, and do not enable macros.
hexagon 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/hexagon/mm/vm_fault.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index f73c7cbfe326..4b578d02fd01 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -93,8 +93,11 @@ void do_page_fault(unsigned long address, long cause,
struct pt_regs *regs)
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;
return;
+ }
/* The fault is fully completed (including releasing mmap lock) */
if (fault & VM_FAULT_COMPLETED)
--
2.30.2
Acked-by: Brian Cain <bcain@xxxxxxxxxxx>
