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linux/arch/x86_64/ia32/ia32_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

623 lines
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/*
* linux/arch/x86_64/ia32/ia32_signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
* 2000-12-* x86-64 compatibility mode signal handling by Andi Kleen
*
* $Id: ia32_signal.c,v 1.22 2002/07/29 10:34:03 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/compat.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/ia32.h>
#include <asm/ptrace.h>
#include <asm/ia32_unistd.h>
#include <asm/user32.h>
#include <asm/sigcontext32.h>
#include <asm/fpu32.h>
#include <asm/proto.h>
#include <asm/vsyscall32.h>
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
{
int err;
if (!access_ok (VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
return -EFAULT;
/* If you change siginfo_t structure, please make sure that
this code is fixed accordingly.
It should never copy any pad contained in the structure
to avoid security leaks, but must copy the generic
3 ints plus the relevant union member. */
err = __put_user(from->si_signo, &to->si_signo);
err |= __put_user(from->si_errno, &to->si_errno);
err |= __put_user((short)from->si_code, &to->si_code);
if (from->si_code < 0) {
err |= __put_user(from->si_pid, &to->si_pid);
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(ptr_to_compat(from->si_ptr), &to->si_ptr);
} else {
/* First 32bits of unions are always present:
* si_pid === si_band === si_tid === si_addr(LS half) */
err |= __put_user(from->_sifields._pad[0], &to->_sifields._pad[0]);
switch (from->si_code >> 16) {
case __SI_FAULT >> 16:
break;
case __SI_CHLD >> 16:
err |= __put_user(from->si_utime, &to->si_utime);
err |= __put_user(from->si_stime, &to->si_stime);
err |= __put_user(from->si_status, &to->si_status);
/* FALL THROUGH */
default:
case __SI_KILL >> 16:
err |= __put_user(from->si_uid, &to->si_uid);
break;
case __SI_POLL >> 16:
err |= __put_user(from->si_fd, &to->si_fd);
break;
case __SI_TIMER >> 16:
err |= __put_user(from->si_overrun, &to->si_overrun);
err |= __put_user(ptr_to_compat(from->si_ptr),
&to->si_ptr);
break;
case __SI_RT >> 16: /* This is not generated by the kernel as of now. */
case __SI_MESGQ >> 16:
err |= __put_user(from->si_uid, &to->si_uid);
err |= __put_user(from->si_int, &to->si_int);
break;
}
}
return err;
}
int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
{
int err;
u32 ptr32;
if (!access_ok (VERIFY_READ, from, sizeof(compat_siginfo_t)))
return -EFAULT;
err = __get_user(to->si_signo, &from->si_signo);
err |= __get_user(to->si_errno, &from->si_errno);
err |= __get_user(to->si_code, &from->si_code);
err |= __get_user(to->si_pid, &from->si_pid);
err |= __get_user(to->si_uid, &from->si_uid);
err |= __get_user(ptr32, &from->si_ptr);
to->si_ptr = compat_ptr(ptr32);
return err;
}
asmlinkage long
sys32_sigsuspend(int history0, int history1, old_sigset_t mask,
struct pt_regs *regs)
{
sigset_t saveset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->rax = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(regs, &saveset))
return -EINTR;
}
}
asmlinkage long
sys32_sigaltstack(const stack_ia32_t __user *uss_ptr,
stack_ia32_t __user *uoss_ptr,
struct pt_regs *regs)
{
stack_t uss,uoss;
int ret;
mm_segment_t seg;
if (uss_ptr) {
u32 ptr;
memset(&uss,0,sizeof(stack_t));
if (!access_ok(VERIFY_READ,uss_ptr,sizeof(stack_ia32_t)) ||
__get_user(ptr, &uss_ptr->ss_sp) ||
__get_user(uss.ss_flags, &uss_ptr->ss_flags) ||
__get_user(uss.ss_size, &uss_ptr->ss_size))
return -EFAULT;
uss.ss_sp = compat_ptr(ptr);
}
seg = get_fs();
set_fs(KERNEL_DS);
ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss, regs->rsp);
set_fs(seg);
if (ret >= 0 && uoss_ptr) {
if (!access_ok(VERIFY_WRITE,uoss_ptr,sizeof(stack_ia32_t)) ||
__put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
__put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
__put_user(uoss.ss_size, &uoss_ptr->ss_size))
ret = -EFAULT;
}
return ret;
}
/*
* Do a signal return; undo the signal stack.
*/
struct sigframe
{
u32 pretcode;
int sig;
struct sigcontext_ia32 sc;
struct _fpstate_ia32 fpstate;
unsigned int extramask[_COMPAT_NSIG_WORDS-1];
char retcode[8];
};
struct rt_sigframe
{
u32 pretcode;
int sig;
u32 pinfo;
u32 puc;
compat_siginfo_t info;
struct ucontext_ia32 uc;
struct _fpstate_ia32 fpstate;
char retcode[8];
};
static int
ia32_restore_sigcontext(struct pt_regs *regs, struct sigcontext_ia32 __user *sc, unsigned int *peax)
{
unsigned int err = 0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
#if DEBUG_SIG
printk("SIG restore_sigcontext: sc=%p err(%x) eip(%x) cs(%x) flg(%x)\n",
sc, sc->err, sc->eip, sc->cs, sc->eflags);
#endif
#define COPY(x) { \
unsigned int reg; \
err |= __get_user(reg, &sc->e ##x); \
regs->r ## x = reg; \
}
#define RELOAD_SEG(seg,mask) \
{ unsigned int cur; \
unsigned short pre; \
err |= __get_user(pre, &sc->seg); \
asm volatile("movl %%" #seg ",%0" : "=r" (cur)); \
pre |= mask; \
if (pre != cur) loadsegment(seg,pre); }
/* Reload fs and gs if they have changed in the signal handler.
This does not handle long fs/gs base changes in the handler, but
does not clobber them at least in the normal case. */
{
unsigned gs, oldgs;
err |= __get_user(gs, &sc->gs);
gs |= 3;
asm("movl %%gs,%0" : "=r" (oldgs));
if (gs != oldgs)
load_gs_index(gs);
}
RELOAD_SEG(fs,3);
RELOAD_SEG(ds,3);
RELOAD_SEG(es,3);
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
COPY(dx); COPY(cx); COPY(ip);
/* Don't touch extended registers */
err |= __get_user(regs->cs, &sc->cs);
regs->cs |= 3;
err |= __get_user(regs->ss, &sc->ss);
regs->ss |= 3;
{
unsigned int tmpflags;
err |= __get_user(tmpflags, &sc->eflags);
regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
regs->orig_rax = -1; /* disable syscall checks */
}
{
u32 tmp;
struct _fpstate_ia32 __user * buf;
err |= __get_user(tmp, &sc->fpstate);
buf = compat_ptr(tmp);
if (buf) {
if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
goto badframe;
err |= restore_i387_ia32(current, buf, 0);
} else {
struct task_struct *me = current;
if (used_math()) {
clear_fpu(me);
clear_used_math();
}
}
}
{
u32 tmp;
err |= __get_user(tmp, &sc->eax);
*peax = tmp;
}
return err;
badframe:
return 1;
}
asmlinkage long sys32_sigreturn(struct pt_regs *regs)
{
struct sigframe __user *frame = (struct sigframe __user *)(regs->rsp-8);
sigset_t set;
unsigned int eax;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_COMPAT_NSIG_WORDS > 1
&& __copy_from_user((((char *) &set.sig) + 4), &frame->extramask,
sizeof(frame->extramask))))
goto badframe;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (ia32_restore_sigcontext(regs, &frame->sc, &eax))
goto badframe;
return eax;
badframe:
signal_fault(regs, frame, "32bit sigreturn");
return 0;
}
asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
sigset_t set;
unsigned int eax;
struct pt_regs tregs;
frame = (struct rt_sigframe __user *)(regs->rsp - 4);
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 (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
goto badframe;
tregs = *regs;
if (sys32_sigaltstack(&frame->uc.uc_stack, NULL, &tregs) == -EFAULT)
goto badframe;
return eax;
badframe:
signal_fault(regs,frame,"32bit rt sigreturn");
return 0;
}
/*
* Set up a signal frame.
*/
static int
ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc, struct _fpstate_ia32 __user *fpstate,
struct pt_regs *regs, unsigned int mask)
{
int tmp, err = 0;
u32 eflags;
tmp = 0;
__asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
__asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
__asm__("movl %%ds,%0" : "=r"(tmp): "0"(tmp));
err |= __put_user(tmp, (unsigned int __user *)&sc->ds);
__asm__("movl %%es,%0" : "=r"(tmp): "0"(tmp));
err |= __put_user(tmp, (unsigned int __user *)&sc->es);
err |= __put_user((u32)regs->rdi, &sc->edi);
err |= __put_user((u32)regs->rsi, &sc->esi);
err |= __put_user((u32)regs->rbp, &sc->ebp);
err |= __put_user((u32)regs->rsp, &sc->esp);
err |= __put_user((u32)regs->rbx, &sc->ebx);
err |= __put_user((u32)regs->rdx, &sc->edx);
err |= __put_user((u32)regs->rcx, &sc->ecx);
err |= __put_user((u32)regs->rax, &sc->eax);
err |= __put_user((u32)regs->cs, &sc->cs);
err |= __put_user((u32)regs->ss, &sc->ss);
err |= __put_user(current->thread.trap_no, &sc->trapno);
err |= __put_user(current->thread.error_code, &sc->err);
err |= __put_user((u32)regs->rip, &sc->eip);
eflags = regs->eflags;
if (current->ptrace & PT_PTRACED)
eflags &= ~TF_MASK;
err |= __put_user((u32)eflags, &sc->eflags);
err |= __put_user((u32)regs->rsp, &sc->esp_at_signal);
tmp = save_i387_ia32(current, fpstate, regs, 0);
if (tmp < 0)
err = -EFAULT;
else {
clear_used_math();
stts();
err |= __put_user(ptr_to_compat(tmp ? fpstate : NULL),
&sc->fpstate);
}
/* non-iBCS2 extensions.. */
err |= __put_user(mask, &sc->oldmask);
err |= __put_user(current->thread.cr2, &sc->cr2);
return err;
}
/*
* Determine which stack to use..
*/
static void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
unsigned long rsp;
/* Default to using normal stack */
rsp = regs->rsp;
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(rsp) == 0)
rsp = current->sas_ss_sp + current->sas_ss_size;
}
/* This is the legacy signal stack switching. */
else if ((regs->ss & 0xffff) != __USER_DS &&
!(ka->sa.sa_flags & SA_RESTORER) &&
ka->sa.sa_restorer) {
rsp = (unsigned long) ka->sa.sa_restorer;
}
return (void __user *)((rsp - frame_size) & -8UL);
}
int ia32_setup_frame(int sig, struct k_sigaction *ka,
compat_sigset_t *set, struct pt_regs * regs)
{
struct sigframe __user *frame;
int err = 0;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
{
struct exec_domain *ed = current_thread_info()->exec_domain;
err |= __put_user((ed
&& ed->signal_invmap
&& sig < 32
? ed->signal_invmap[sig]
: sig),
&frame->sig);
}
if (err)
goto give_sigsegv;
err |= ia32_setup_sigcontext(&frame->sc, &frame->fpstate, regs,
set->sig[0]);
if (err)
goto give_sigsegv;
if (_COMPAT_NSIG_WORDS > 1) {
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
}
if (err)
goto give_sigsegv;
/* Return stub is in 32bit vsyscall page */
{
void __user *restorer = VSYSCALL32_SIGRETURN;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
}
/* These are actually not used anymore, but left because some
gdb versions depend on them as a marker. */
{
/* copy_to_user optimizes that into a single 8 byte store */
static const struct {
u16 poplmovl;
u32 val;
u16 int80;
u16 pad;
} __attribute__((packed)) code = {
0xb858, /* popl %eax ; movl $...,%eax */
__NR_ia32_sigreturn,
0x80cd, /* int $0x80 */
0,
};
err |= __copy_to_user(frame->retcode, &code, 8);
}
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->rsp = (unsigned long) frame;
regs->rip = (unsigned long) ka->sa.sa_handler;
asm volatile("movl %0,%%ds" :: "r" (__USER32_DS));
asm volatile("movl %0,%%es" :: "r" (__USER32_DS));
regs->cs = __USER32_CS;
regs->ss = __USER32_DS;
set_fs(USER_DS);
if (regs->eflags & TF_MASK) {
if (current->ptrace & PT_PTRACED) {
ptrace_notify(SIGTRAP);
} else {
regs->eflags &= ~TF_MASK;
}
}
#if 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;
}
int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
compat_sigset_t *set, struct pt_regs * regs)
{
struct rt_sigframe __user *frame;
int err = 0;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
{
struct exec_domain *ed = current_thread_info()->exec_domain;
err |= __put_user((ed
&& ed->signal_invmap
&& sig < 32
? ed->signal_invmap[sig]
: sig),
&frame->sig);
}
err |= __put_user(ptr_to_compat(&frame->info), &frame->pinfo);
err |= __put_user(ptr_to_compat(&frame->uc), &frame->puc);
err |= copy_siginfo_to_user32(&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(current->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(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
goto give_sigsegv;
{
void __user *restorer = VSYSCALL32_RTSIGRETURN;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
}
/* This is movl $,%eax ; int $0x80 */
/* Not actually used anymore, but left because some gdb versions
need it. */
{
/* __copy_to_user optimizes that into a single 8 byte store */
static const struct {
u8 movl;
u32 val;
u16 int80;
u16 pad;
u8 pad2;
} __attribute__((packed)) code = {
0xb8,
__NR_ia32_rt_sigreturn,
0x80cd,
0,
};
err |= __copy_to_user(frame->retcode, &code, 8);
}
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->rsp = (unsigned long) frame;
regs->rip = (unsigned long) ka->sa.sa_handler;
asm volatile("movl %0,%%ds" :: "r" (__USER32_DS));
asm volatile("movl %0,%%es" :: "r" (__USER32_DS));
regs->cs = __USER32_CS;
regs->ss = __USER32_DS;
set_fs(USER_DS);
if (regs->eflags & TF_MASK) {
if (current->ptrace & PT_PTRACED) {
ptrace_notify(SIGTRAP);
} else {
regs->eflags &= ~TF_MASK;
}
}
#if 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;
}
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