Messages in this thread | | | Subject | Re: [PATCH v2 13/19] x86/signal: Check if vdso_image_32 is mapped before trying to land on it | From | Dmitry Safonov <> | Date | Thu, 26 Nov 2020 20:00:17 +0000 |
| |
On 11/24/20 11:43 PM, Andy Lutomirski wrote: > On Mon, Nov 23, 2020 at 4:29 PM Dmitry Safonov <dima@arista.com> wrote: >> >> Provide current_has_vdso_image_32() helper and check it apriory landing >> attempt on vdso vma. >> The helper is a macro, not a static inline funciton to avoid >> linux/sched/task_stack.h inclusion in asm/vdso.h. > > Can you make this more general? For example: > > current_has_vdso(&vdso_image_whatever)
Sounds good, will do.
> > also: > >> diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c >> index 18d8f17f755c..d9ab58cc765b 100644 >> --- a/arch/x86/entry/common.c >> +++ b/arch/x86/entry/common.c >> @@ -142,11 +142,16 @@ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs) >> /* Returns 0 to return using IRET or 1 to return using SYSEXIT/SYSRETL. */ >> __visible noinstr long do_fast_syscall_32(struct pt_regs *regs) >> { >> + unsigned long landing_pad; >> + >> + if (!current_has_vdso_image_32()) >> + force_sigsegv(SIGSEGV); > > Falling through seems incorrect here. I would instead write 0 to rip, > do the force_sigsegv(), and exit, making sure that exiting goes > through the correct path. >
Something like this?
: if (!current_has_vdso(&vdso_image_32)) { : regs->ax = -EFAULT; : regs->ip = 0; : force_sigsegv(SIGSEGV); : syscall_exit_to_user_mode(regs); : }
Thanks, Dmitry
| |