lisa/android_kernel_xiaomi_sm8350
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
7c1def1652
android_kernel_xiaomi_sm8350/arch/i386/kernel/signal.c
Roland McGrath 7c1def1652 [PATCH] i386: never block forced SIGSEGV 
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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 09:45:09 -07:00

671 lines
17 KiB
C
Raw Blame History

/*
* linux/arch/i386/kernel/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
*/
#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/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/suspend.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include "sigframe.h"
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int
sys_sigsuspend(int history0, int history1, old_sigset_t mask)
{
struct pt_regs * regs = (struct pt_regs *) &history0;
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->eax = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(regs, &saveset))
return -EINTR;
}
}
asmlinkage int
sys_rt_sigsuspend(struct pt_regs regs)
{
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (regs.ecx != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, (sigset_t __user *)regs.ebx, 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);
regs.eax = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&regs, &saveset))
return -EINTR;
}
}
asmlinkage int
sys_sigaction(int sig, const struct old_sigaction __user *act,
struct old_sigaction __user *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
return -EFAULT;
__get_user(new_ka.sa.sa_flags, &act->sa_flags);
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
return -EFAULT;
__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
asmlinkage int
sys_sigaltstack(unsigned long ebx)
{
/* This is needed to make gcc realize it doesn't own the "struct pt_regs" */
struct pt_regs *regs = (struct pt_regs *)&ebx;
const stack_t __user *uss = (const stack_t __user *)ebx;
stack_t __user *uoss = (stack_t __user *)regs->ecx;
return do_sigaltstack(uss, uoss, regs->esp);
}
/*
* Do a signal return; undo the signal stack.
*/
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, 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;
#define COPY(x) err |= __get_user(regs->x, &sc->x)
#define COPY_SEG(seg) \
{ unsigned short tmp; \
err |= __get_user(tmp, &sc->seg); \
regs->x##seg = tmp; }
#define COPY_SEG_STRICT(seg) \
{ unsigned short tmp; \
err |= __get_user(tmp, &sc->seg); \
regs->x##seg = tmp|3; }
#define GET_SEG(seg) \
{ unsigned short tmp; \
err |= __get_user(tmp, &sc->seg); \
loadsegment(seg,tmp); }
#define FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | X86_EFLAGS_DF | \
X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \
X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF)
GET_SEG(gs);
GET_SEG(fs);
COPY_SEG(es);
COPY_SEG(ds);
COPY(edi);
COPY(esi);
COPY(ebp);
COPY(esp);
COPY(ebx);
COPY(edx);
COPY(ecx);
COPY(eip);
COPY_SEG_STRICT(cs);
COPY_SEG_STRICT(ss);
{
unsigned int tmpflags;
err |= __get_user(tmpflags, &sc->eflags);
regs->eflags = (regs->eflags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
regs->orig_eax = -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(*peax, &sc->eax);
return err;
badframe:
return 1;
}
asmlinkage int sys_sigreturn(unsigned long __unused)
{
struct pt_regs *regs = (struct pt_regs *) &__unused;
struct sigframe __user *frame = (struct sigframe __user *)(regs->esp - 8);
sigset_t set;
int eax;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_NSIG_WORDS > 1
&& __copy_from_user(&set.sig[1], &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 (restore_sigcontext(regs, &frame->sc, &eax))
goto badframe;
return eax;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(unsigned long __unused)
{
struct pt_regs *regs = (struct pt_regs *) &__unused;
struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->esp - 4);
sigset_t set;
int eax;
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;
if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT)
goto badframe;
return eax;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
static int
setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
struct pt_regs *regs, unsigned long mask)
{
int tmp, err = 0;
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);
err |= __put_user(regs->xes, (unsigned int __user *)&sc->es);
err |= __put_user(regs->xds, (unsigned int __user *)&sc->ds);
err |= __put_user(regs->edi, &sc->edi);
err |= __put_user(regs->esi, &sc->esi);
err |= __put_user(regs->ebp, &sc->ebp);
err |= __put_user(regs->esp, &sc->esp);
err |= __put_user(regs->ebx, &sc->ebx);
err |= __put_user(regs->edx, &sc->edx);
err |= __put_user(regs->ecx, &sc->ecx);
err |= __put_user(regs->eax, &sc->eax);
err |= __put_user(current->thread.trap_no, &sc->trapno);
err |= __put_user(current->thread.error_code, &sc->err);
err |= __put_user(regs->eip, &sc->eip);
err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs);
err |= __put_user(regs->eflags, &sc->eflags);
err |= __put_user(regs->esp, &sc->esp_at_signal);
err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss);
tmp = save_i387(fpstate);
if (tmp < 0)
err = 1;
else
err |= __put_user(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 inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
unsigned long esp;
/* Default to using normal stack */
esp = regs->esp;
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(esp) == 0)
esp = current->sas_ss_sp + current->sas_ss_size;
}
/* This is the legacy signal stack switching. */
else if ((regs->xss & 0xffff) != __USER_DS &&
!(ka->sa.sa_flags & SA_RESTORER) &&
ka->sa.sa_restorer) {
esp = (unsigned long) ka->sa.sa_restorer;
}
return (void __user *)((esp - frame_size) & -8ul);
}
/* These symbols are defined with the addresses in the vsyscall page.
See vsyscall-sigreturn.S. */
extern void __user __kernel_sigreturn;
extern void __user __kernel_rt_sigreturn;
static int setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs * regs)
{
void __user *restorer;
struct sigframe __user *frame;
int err = 0;
int usig;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
usig = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err = __put_user(usig, &frame->sig);
if (err)
goto give_sigsegv;
err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
if (err)
goto give_sigsegv;
if (_NSIG_WORDS > 1) {
err = __copy_to_user(&frame->extramask, &set->sig[1],
sizeof(frame->extramask));
if (err)
goto give_sigsegv;
}
restorer = &__kernel_sigreturn;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
/* Set up to return from userspace. */
err |= __put_user(restorer, &frame->pretcode);
/*
* This is popl %eax ; movl $,%eax ; int $0x80
*
* WE DO NOT USE IT ANY MORE! It's only left here for historical
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->esp = (unsigned long) frame;
regs->eip = (unsigned long) ka->sa.sa_handler;
regs->eax = (unsigned long) sig;
regs->edx = (unsigned long) 0;
regs->ecx = (unsigned long) 0;
set_fs(USER_DS);
regs->xds = __USER_DS;
regs->xes = __USER_DS;
regs->xss = __USER_DS;
regs->xcs = __USER_CS;
/*
* Clear TF when entering the signal handler, but
* notify any tracer that was single-stepping it.
* The tracer may want to single-step inside the
* handler too.
*/
regs->eflags &= ~TF_MASK;
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->eip, frame->pretcode);
#endif
return 1;
give_sigsegv:
force_sigsegv(sig, current);
return 0;
}
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs * regs)
{
void __user *restorer;
struct rt_sigframe __user *frame;
int err = 0;
int usig;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
usig = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err |= __put_user(usig, &frame->sig);
err |= __put_user(&frame->info, &frame->pinfo);
err |= __put_user(&frame->uc, &frame->puc);
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(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->esp),
&frame->uc.uc_stack.ss_flags);
err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= 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;
/* Set up to return from userspace. */
restorer = &__kernel_rt_sigreturn;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
err |= __put_user(restorer, &frame->pretcode);
/*
* This is movl $,%eax ; int $0x80
*
* WE DO NOT USE IT ANY MORE! It's only left here for historical
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->esp = (unsigned long) frame;
regs->eip = (unsigned long) ka->sa.sa_handler;
regs->eax = (unsigned long) usig;
regs->edx = (unsigned long) &frame->info;
regs->ecx = (unsigned long) &frame->uc;
set_fs(USER_DS);
regs->xds = __USER_DS;
regs->xes = __USER_DS;
regs->xss = __USER_DS;
regs->xcs = __USER_CS;
/*
* Clear TF when entering the signal handler, but
* notify any tracer that was single-stepping it.
* The tracer may want to single-step inside the
* handler too.
*/
regs->eflags &= ~TF_MASK;
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->eip, 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;
/* Are we from a system call? */
if (regs->orig_eax >= 0) {
/* If so, check system call restarting.. */
switch (regs->eax) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->eax = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->eax = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
regs->eax = regs->orig_eax;
regs->eip -= 2;
}
}
/*
* 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)
&& likely(current->ptrace & PT_DTRACE)) {
current->ptrace &= ~PT_DTRACE;
regs->eflags &= ~TF_MASK;
}
/* Set up the stack frame */
if (ka->sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(sig, ka, info, oldset, regs);
else
ret = setup_frame(sig, ka, 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 fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
{
siginfo_t info;
int signr;
struct k_sigaction ka;
/*
* 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->xcs & 3) != 3)
return 1;
if (current->flags & PF_FREEZE) {
refrigerator(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 (unlikely(current->thread.debugreg[7])) {
loaddebug(&current->thread, 7);
}
/* Whee! Actually deliver the signal. */
return handle_signal(signr, &info, &ka, oldset, regs);
}
no_signal:
/* Did we come from a system call? */
if (regs->orig_eax >= 0) {
/* Restart the system call - no handlers present */
if (regs->eax == -ERESTARTNOHAND ||
regs->eax == -ERESTARTSYS ||
regs->eax == -ERESTARTNOINTR) {
regs->eax = regs->orig_eax;
regs->eip -= 2;
}
if (regs->eax == -ERESTART_RESTARTBLOCK){
regs->eax = __NR_restart_syscall;
regs->eip -= 2;
}
}
return 0;
}
/*
* notification of userspace execution resumption
* - triggered by current->work.notify_resume
*/
__attribute__((regparm(3)))
void do_notify_resume(struct pt_regs *regs, sigset_t *oldset,
__u32 thread_info_flags)
{
/* 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);
clear_thread_flag(TIF_IRET);
}
Reference in New Issue View Git Blame Copy Permalink