| Message ID | Y9l0LyAA3zAGeT51@ZenIV |
|---|---|
| State | New |
| Headers | show |
| Series | [01/10] alpha: fix livelock in uaccess | expand |
> -----Original Message----- > From: Al Viro <viro@ftp.linux.org.uk> On Behalf Of Al Viro > Sent: Tuesday, January 31, 2023 2:04 PM > To: linux-arch@vger.kernel.org > Cc: linux-alpha@vger.kernel.org; linux-ia64@vger.kernel.org; linux- > hexagon@vger.kernel.org; linux-m68k@lists.linux-m68k.org; Michal Simek > <monstr@monstr.eu>; Dinh Nguyen <dinguyen@kernel.org>; > openrisc@lists.librecores.org; linux-parisc@vger.kernel.org; linux- > riscv@lists.infradead.org; sparclinux@vger.kernel.org; Linus Torvalds > <torvalds@linux-foundation.org> > 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@zeniv.linux.org.uk> > --- > 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@quicinc.com>
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)
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@zeniv.linux.org.uk> --- arch/hexagon/mm/vm_fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)