AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-12-12 03:56:50 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity
0928d6ef7f
linux_dsm_epyc7002/arch/x86_64/kernel/signal.c
Roland McGrath 0928d6ef7f [PATCH] x86_64: never block forced SIGSEGV 
This is the x86_64 version of the signal fix I just posted for i386.

This problem was first noticed on PPC and has already been fixed there.
But the exact same issue applies to other platforms in the same way.  The
signal blocking for sa_mask and the handled signal takes place after the
handler setup.  When the stack is bogus, the handler setup forces a
SIGSEGV.  But then this will be blocked, and returning to user mode will
fault again and iterate.  This patch fixes the problem by checking whether
signal handler setup failed, and not doing the signal-blocking if so.  This
copies what was done in the ppc code.  I think all architectures' signal
handler setup code follows this pattern and needs the change.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 09:45:13 -07:00

496 lines
13 KiB
C
Raw Blame History

/*
* linux/arch/x86_64/kernel/signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
* 2000-2002 x86-64 support by Andi Kleen
*
* $Id: signal.c,v 1.18 2001/10/17 22:30:37 ak Exp $
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compiler.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/proto.h>
#include <asm/ia32_unistd.h>
/* #define DEBUG_SIG 1 */
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs * regs);
int ia32_setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs * regs);
asmlinkage long
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
{
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, unewset, sizeof(newset)))
return -EFAULT;
sigdelsetmask(&newset, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
#ifdef DEBUG_SIG
printk("rt_sigsuspend savset(%lx) newset(%lx) regs(%p) rip(%lx)\n",
saveset, newset, regs, regs->rip);
#endif
regs->rax = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(regs, &saveset))
return -EINTR;
}
}
asmlinkage long
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
struct pt_regs *regs)
{
return do_sigaltstack(uss, uoss, regs->rsp);
}
/*
* Do a signal return; undo the signal stack.
*/
struct rt_sigframe
{
char __user *pretcode;
struct ucontext uc;
struct siginfo info;
};
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
{
unsigned int err = 0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
#define COPY(x) err |= __get_user(regs->x, &sc->x)
COPY(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
COPY(rdx); COPY(rcx); COPY(rip);
COPY(r8);
COPY(r9);
COPY(r10);
COPY(r11);
COPY(r12);
COPY(r13);
COPY(r14);
COPY(r15);
{
unsigned int tmpflags;
err |= __get_user(tmpflags, &sc->eflags);
regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
regs->orig_rax = -1; /* disable syscall checks */
}
{
struct _fpstate __user * buf;
err |= __get_user(buf, &sc->fpstate);
if (buf) {
if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
goto badframe;
err |= restore_i387(buf);
} else {
struct task_struct *me = current;
if (used_math()) {
clear_fpu(me);
clear_used_math();
}
}
}
err |= __get_user(*prax, &sc->rax);
return err;
badframe:
return 1;
}
asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
sigset_t set;
unsigned long eax;
frame = (struct rt_sigframe __user *)(regs->rsp - 8);
if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
goto badframe;
}
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
goto badframe;
}
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
goto badframe;
#ifdef DEBUG_SIG
printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs.rip,regs.rsp,frame,eax);
#endif
if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
goto badframe;
return eax;
badframe:
signal_fault(regs,frame,"sigreturn");
return 0;
}
/*
* Set up a signal frame.
*/
static inline int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
{
int err = 0;
err |= __put_user(0, &sc->gs);
err |= __put_user(0, &sc->fs);
err |= __put_user(regs->rdi, &sc->rdi);
err |= __put_user(regs->rsi, &sc->rsi);
err |= __put_user(regs->rbp, &sc->rbp);
err |= __put_user(regs->rsp, &sc->rsp);
err |= __put_user(regs->rbx, &sc->rbx);
err |= __put_user(regs->rdx, &sc->rdx);
err |= __put_user(regs->rcx, &sc->rcx);
err |= __put_user(regs->rax, &sc->rax);
err |= __put_user(regs->r8, &sc->r8);
err |= __put_user(regs->r9, &sc->r9);
err |= __put_user(regs->r10, &sc->r10);
err |= __put_user(regs->r11, &sc->r11);
err |= __put_user(regs->r12, &sc->r12);
err |= __put_user(regs->r13, &sc->r13);
err |= __put_user(regs->r14, &sc->r14);
err |= __put_user(regs->r15, &sc->r15);
err |= __put_user(me->thread.trap_no, &sc->trapno);
err |= __put_user(me->thread.error_code, &sc->err);
err |= __put_user(regs->rip, &sc->rip);
err |= __put_user(regs->eflags, &sc->eflags);
err |= __put_user(mask, &sc->oldmask);
err |= __put_user(me->thread.cr2, &sc->cr2);
return err;
}
/*
* Determine which stack to use..
*/
static void __user *
get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
{
unsigned long rsp;
/* Default to using normal stack - redzone*/
rsp = regs->rsp - 128;
/* This is the X/Open sanctioned signal stack switching. */
/* RED-PEN: redzone on that stack? */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(rsp) == 0)
rsp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *)round_down(rsp - size, 16);
}
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs * regs)
{
struct rt_sigframe __user *frame;
struct _fpstate __user *fp = NULL;
int err = 0;
struct task_struct *me = current;
if (used_math()) {
fp = get_stack(ka, regs, sizeof(struct _fpstate));
frame = (void __user *)round_down(
(unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
goto give_sigsegv;
if (save_i387(fp) < 0)
err |= -1;
} else
frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
if (ka->sa.sa_flags & SA_SIGINFO) {
err |= copy_siginfo_to_user(&frame->info, info);
if (err)
goto give_sigsegv;
}
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->rsp),
&frame->uc.uc_stack.ss_flags);
err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
if (sizeof(*set) == 16) {
__put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
__put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
} else
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
/* x86-64 should always use SA_RESTORER. */
if (ka->sa.sa_flags & SA_RESTORER) {
err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
} else {
/* could use a vstub here */
goto give_sigsegv;
}
if (err)
goto give_sigsegv;
#ifdef DEBUG_SIG
printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
#endif
/* Set up registers for signal handler */
{
struct exec_domain *ed = current_thread_info()->exec_domain;
if (unlikely(ed && ed->signal_invmap && sig < 32))
sig = ed->signal_invmap[sig];
}
regs->rdi = sig;
/* In case the signal handler was declared without prototypes */
regs->rax = 0;
/* This also works for non SA_SIGINFO handlers because they expect the
next argument after the signal number on the stack. */
regs->rsi = (unsigned long)&frame->info;
regs->rdx = (unsigned long)&frame->uc;
regs->rip = (unsigned long) ka->sa.sa_handler;
regs->rsp = (unsigned long)frame;
set_fs(USER_DS);
regs->eflags &= ~TF_MASK;
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#ifdef DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->rip, frame->pretcode);
#endif
return 1;
give_sigsegv:
force_sigsegv(sig, current);
return 0;
}
/*
* OK, we're invoking a handler
*/
static int
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
sigset_t *oldset, struct pt_regs *regs)
{
int ret;
#ifdef DEBUG_SIG
printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
current->pid, sig,
regs->rip, regs->rsp, regs);
#endif
/* Are we from a system call? */
if ((long)regs->orig_rax >= 0) {
/* If so, check system call restarting.. */
switch (regs->rax) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->rax = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->rax = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
regs->rax = regs->orig_rax;
regs->rip -= 2;
break;
}
}
/*
* If TF is set due to a debugger (PT_DTRACE), clear the TF
* flag so that register information in the sigcontext is
* correct.
*/
if (unlikely(regs->eflags & TF_MASK)) {
if (likely(current->ptrace & PT_DTRACE)) {
current->ptrace &= ~PT_DTRACE;
regs->eflags &= ~TF_MASK;
}
}
#ifdef CONFIG_IA32_EMULATION
if (test_thread_flag(TIF_IA32)) {
if (ka->sa.sa_flags & SA_SIGINFO)
ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
else
ret = ia32_setup_frame(sig, ka, oldset, regs);
} else
#endif
ret = setup_rt_frame(sig, ka, info, oldset, regs);
if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
sigaddset(&current->blocked,sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
return ret;
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*/
int do_signal(struct pt_regs *regs, sigset_t *oldset)
{
struct k_sigaction ka;
siginfo_t info;
int signr;
/*
* We want the common case to go fast, which
* is why we may in certain cases get here from
* kernel mode. Just return without doing anything
* if so.
*/
if ((regs->cs & 3) != 3)
return 1;
if (try_to_freeze(0))
goto no_signal;
if (!oldset)
oldset = &current->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
/* Reenable any watchpoints before delivering the
* signal to user space. The processor register will
* have been cleared if the watchpoint triggered
* inside the kernel.
*/
if (current->thread.debugreg7)
asm volatile("movq %0,%%db7" : : "r" (current->thread.debugreg7));
/* Whee! Actually deliver the signal. */
return handle_signal(signr, &info, &ka, oldset, regs);
}
no_signal:
/* Did we come from a system call? */
if ((long)regs->orig_rax >= 0) {
/* Restart the system call - no handlers present */
long res = regs->rax;
if (res == -ERESTARTNOHAND ||
res == -ERESTARTSYS ||
res == -ERESTARTNOINTR) {
regs->rax = regs->orig_rax;
regs->rip -= 2;
}
if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
regs->rax = test_thread_flag(TIF_IA32) ?
__NR_ia32_restart_syscall :
__NR_restart_syscall;
regs->rip -= 2;
}
}
return 0;
}
void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
{
#ifdef DEBUG_SIG
printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
#endif
/* Pending single-step? */
if (thread_info_flags & _TIF_SINGLESTEP) {
regs->eflags |= TF_MASK;
clear_thread_flag(TIF_SINGLESTEP);
}
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs,oldset);
}
void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
{
struct task_struct *me = current;
if (exception_trace)
printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
force_sig(SIGSEGV, me);
}
Reference in New Issue View Git Blame Copy Permalink