[PATCH] signal-race fixes for ppc32 and ppc64

From: Paul Mackerras
Date: Sun Mar 28 2004 - 06:39:49 EST

Andrew,

I see that the patch to fix the race in do_signal is in -mm4. Here is
a patch to make the corresponding changes for ppc32 and ppc64.

Paul.

diff -urN linux-2.6.5-rc2-mm4.orig/arch/ppc/kernel/signal.c linux-2.6.5-rc2-mm4/arch/ppc/kernel/signal.c
--- linux-2.6.5-rc2-mm4.orig/arch/ppc/kernel/signal.c 2004-03-28 15:46:13.871883656 +1000
+++ linux-2.6.5-rc2-mm4/arch/ppc/kernel/signal.c 2004-03-28 15:59:36.062884112 +1000
@@ -306,7 +306,7 @@
* (one which gets siginfo).
*/
static void
-handle_rt_signal(unsigned long sig, struct k_sigaction *ka,
+handle_rt_signal(unsigned long sig, struct k_sigaction *ka_copy,
siginfo_t *info, sigset_t *oldset, struct pt_regs * regs,
unsigned long newsp)
{
@@ -349,7 +349,7 @@
regs->gpr[4] = (unsigned long) &rt_sf->info;
regs->gpr[5] = (unsigned long) &rt_sf->uc;
regs->gpr[6] = (unsigned long) rt_sf;
- regs->nip = (unsigned long) ka->sa.sa_handler;
+ regs->nip = (unsigned long) ka_copy->sa.sa_handler;
regs->link = (unsigned long) frame->tramp;
regs->trap = 0;

@@ -361,7 +361,7 @@
regs, frame, newsp);
#endif
if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
+ current->sighand->action[SIGSEGV-1].sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}

@@ -461,7 +461,7 @@
* OK, we're invoking a handler
*/
static void
-handle_signal(unsigned long sig, struct k_sigaction *ka,
+handle_signal(unsigned long sig, struct k_sigaction *ka_copy,
siginfo_t *info, sigset_t *oldset, struct pt_regs * regs,
unsigned long newsp)
{
@@ -486,7 +486,7 @@
#if _NSIG != 64
#error "Please adjust handle_signal()"
#endif
- if (__put_user((unsigned long) ka->sa.sa_handler, &sc->handler)
+ if (__put_user((unsigned long) ka_copy->sa.sa_handler, &sc->handler)
|| __put_user(oldset->sig[0], &sc->oldmask)
|| __put_user(oldset->sig[1], &sc->_unused[3])
|| __put_user((struct pt_regs *)frame, &sc->regs)
@@ -501,7 +501,7 @@
regs->gpr[1] = newsp;
regs->gpr[3] = sig;
regs->gpr[4] = (unsigned long) sc;
- regs->nip = (unsigned long) ka->sa.sa_handler;
+ regs->nip = (unsigned long) ka_copy->sa.sa_handler;
regs->link = (unsigned long) frame->mctx.tramp;
regs->trap = 0;

@@ -513,7 +513,7 @@
regs, frame, *newspp);
#endif
if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
+ current->sighand->action[SIGSEGV-1].sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}

@@ -560,18 +560,16 @@
int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
siginfo_t info;
- struct k_sigaction *ka;
unsigned long frame, newsp;
int signr, ret;
+ struct k_sigaction ka_copy;

if (!oldset)
oldset = &current->blocked;

newsp = frame = 0;

- signr = get_signal_to_deliver(&info, regs, NULL);
-
- ka = (signr == 0)? NULL: &current->sighand->action[signr-1];
+ signr = get_signal_to_deliver(&info, &ka_copy, regs, NULL);

if (TRAP(regs) == 0x0C00 /* System Call! */
&& regs->ccr & 0x10000000 /* error signalled */
@@ -582,7 +580,7 @@
if (signr > 0
&& (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
|| (ret == ERESTARTSYS
- && !(ka->sa.sa_flags & SA_RESTART)))) {
+ && !(ka_copy.sa.sa_flags & SA_RESTART)))) {
/* make the system call return an EINTR error */
regs->result = -EINTR;
regs->gpr[3] = EINTR;
@@ -601,7 +599,7 @@
if (signr == 0)
return 0; /* no signals delivered */

- if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
+ if ((ka_copy.sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
&& !on_sig_stack(regs->gpr[1]))
newsp = current->sas_ss_sp + current->sas_ss_size;
else
@@ -609,17 +607,18 @@
newsp &= ~0xfUL;

/* Whee! Actually deliver the signal. */
- if (ka->sa.sa_flags & SA_SIGINFO)
- handle_rt_signal(signr, ka, &info, oldset, regs, newsp);
+ if (ka_copy.sa.sa_flags & SA_SIGINFO)
+ handle_rt_signal(signr, &ka_copy, &info, oldset, regs, newsp);
else
- handle_signal(signr, ka, &info, oldset, regs, newsp);
+ handle_signal(signr, &ka_copy, &info, oldset, regs, newsp);

- if (ka->sa.sa_flags & SA_ONESHOT)
- ka->sa.sa_handler = SIG_DFL;
+ if (ka_copy.sa.sa_flags & SA_ONESHOT)
+ ka_copy.sa.sa_handler = SIG_DFL;

- if (!(ka->sa.sa_flags & SA_NODEFER)) {
+ if (!(ka_copy.sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&current->sighand->siglock);
- sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+ sigorsets(&current->blocked, &current->blocked,
+ &ka_copy.sa.sa_mask);
sigaddset(&current->blocked, signr);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
diff -urN linux-2.6.5-rc2-mm4.orig/arch/ppc64/kernel/signal.c linux-2.6.5-rc2-mm4/arch/ppc64/kernel/signal.c
--- linux-2.6.5-rc2-mm4.orig/arch/ppc64/kernel/signal.c 2004-03-28 15:44:32.215895664 +1000
+++ linux-2.6.5-rc2-mm4/arch/ppc64/kernel/signal.c 2004-03-28 14:57:58.000000000 +1000
@@ -216,15 +216,15 @@
/*
* Allocate space for the signal frame
*/
-static inline void * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
- size_t frame_size)
+static inline void * get_sigframe(struct k_sigaction *ka_copy,
+ struct pt_regs *regs, size_t frame_size)
{
unsigned long newsp;

/* Default to using normal stack */
newsp = regs->gpr[1];

- if (ka->sa.sa_flags & SA_ONSTACK) {
+ if (ka_copy->sa.sa_flags & SA_ONSTACK) {
if (! on_sig_stack(regs->gpr[1]))
newsp = (current->sas_ss_sp + current->sas_ss_size);
}
@@ -361,8 +361,8 @@
do_exit(SIGSEGV);
}

-static void setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
- sigset_t *set, struct pt_regs *regs)
+static void setup_rt_frame(int signr, struct k_sigaction *ka_copy,
+ siginfo_t *info, sigset_t *set, struct pt_regs *regs)
{
/* Handler is *really* a pointer to the function descriptor for
* the signal routine. The first entry in the function
@@ -374,7 +374,7 @@
unsigned long newsp = 0;
int err = 0;

- frame = get_sigframe(ka, regs, sizeof(*frame));
+ frame = get_sigframe(ka_copy, regs, sizeof(*frame));

if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
goto badframe;
@@ -393,7 +393,7 @@
&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, regs, signr, NULL,
- (unsigned long)ka->sa.sa_handler);
+ (unsigned long)ka_copy->sa.sa_handler);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
goto badframe;
@@ -403,7 +403,7 @@
if (err)
goto badframe;

- funct_desc_ptr = (func_descr_t *) ka->sa.sa_handler;
+ funct_desc_ptr = (func_descr_t *) ka_copy->sa.sa_handler;

/* Allocate a dummy caller frame for the signal handler. */
newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
@@ -415,7 +415,7 @@
regs->gpr[1] = newsp;
err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
regs->gpr[3] = signr;
- if (ka->sa.sa_flags & SA_SIGINFO) {
+ if (ka_copy->sa.sa_flags & SA_SIGINFO) {
err |= get_user(regs->gpr[4], (unsigned long *)&frame->pinfo);
err |= get_user(regs->gpr[5], (unsigned long *)&frame->puc);
regs->gpr[6] = (unsigned long) frame;
@@ -432,33 +432,33 @@
printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
regs, frame, newsp);
#endif
- do_exit(SIGSEGV);
+ if (signr == SIGSEGV)
+ current->sighand->action[SIGSEGV-1].sa.sa_handler = SIG_DFL;
+ force_sig(SIGSEGV, current);
}


/*
* OK, we're invoking a handler
*/
-static void handle_signal(unsigned long sig, struct k_sigaction *ka,
- siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
+static void handle_signal(unsigned long sig, struct k_sigaction *ka_copy,
+ siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
/* Set up Signal Frame */
- setup_rt_frame(sig, ka, info, oldset, regs);
-
- if (ka->sa.sa_flags & SA_ONESHOT)
- ka->sa.sa_handler = SIG_DFL;
+ setup_rt_frame(sig, ka_copy, info, oldset, regs);

- if (!(ka->sa.sa_flags & SA_NODEFER)) {
+ if (!(ka_copy->sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&current->sighand->siglock);
- sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+ sigorsets(&current->blocked, &current->blocked,
+ &ka_copy->sa.sa_mask);
sigaddset(&current->blocked,sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
- return;
}

-static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
+static inline void syscall_restart(struct pt_regs *regs,
+ struct k_sigaction *ka_copy)
{
switch ((int)regs->result) {
case -ERESTART_RESTARTBLOCK:
@@ -473,7 +473,7 @@
/* ERESTARTSYS means to restart the syscall if there is no
* handler or the handler was registered with SA_RESTART
*/
- if (!(ka->sa.sa_flags & SA_RESTART)) {
+ if (!(ka_copy->sa.sa_flags & SA_RESTART)) {
regs->result = -EINTR;
break;
}
@@ -498,6 +498,7 @@
{
siginfo_t info;
int signr;
+ struct k_sigaction ka_copy;

/*
* If the current thread is 32 bit - invoke the
@@ -509,14 +510,12 @@
if (!oldset)
oldset = &current->blocked;

- signr = get_signal_to_deliver(&info, regs, NULL);
+ signr = get_signal_to_deliver(&info, &ka_copy, regs, NULL);
if (signr > 0) {
- struct k_sigaction *ka = &current->sighand->action[signr-1];
-
/* Whee! Actually deliver the signal. */
if (regs->trap == 0x0C00)
- syscall_restart(regs, ka);
- handle_signal(signr, ka, &info, oldset, regs);
+ syscall_restart(regs, &ka_copy);
+ handle_signal(signr, &ka_copy, &info, oldset, regs);
return 1;
}

diff -urN linux-2.6.5-rc2-mm4.orig/arch/ppc64/kernel/signal32.c linux-2.6.5-rc2-mm4/arch/ppc64/kernel/signal32.c
--- linux-2.6.5-rc2-mm4.orig/arch/ppc64/kernel/signal32.c 2004-03-28 15:45:56.794951080 +1000
+++ linux-2.6.5-rc2-mm4/arch/ppc64/kernel/signal32.c 2004-03-28 14:58:34.000000000 +1000
@@ -657,7 +657,7 @@
* Set up a signal frame for a "real-time" signal handler
* (one which gets siginfo).
*/
-static void handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
+static void handle_rt_signal32(unsigned long sig, struct k_sigaction *ka_copy,
siginfo_t *info, sigset_t *oldset,
struct pt_regs * regs, unsigned long newsp)
{
@@ -703,7 +703,7 @@
regs->gpr[4] = (unsigned long) &rt_sf->info;
regs->gpr[5] = (unsigned long) &rt_sf->uc;
regs->gpr[6] = (unsigned long) rt_sf;
- regs->nip = (unsigned long) ka->sa.sa_handler;
+ regs->nip = (unsigned long) ka_copy->sa.sa_handler;
regs->link = (unsigned long) frame->tramp;
regs->trap = 0;

@@ -715,7 +715,7 @@
regs, frame, newsp);
#endif
if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
+ current->sighand->action[SIGSEGV-1].sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}

@@ -828,7 +828,7 @@
/*
* OK, we're invoking a handler
*/
-static void handle_signal32(unsigned long sig, struct k_sigaction *ka,
+static void handle_signal32(unsigned long sig, struct k_sigaction *ka_copy,
siginfo_t *info, sigset_t *oldset,
struct pt_regs * regs, unsigned long newsp)
{
@@ -853,7 +853,7 @@
#if _NSIG != 64
#error "Please adjust handle_signal32()"
#endif
- if (__put_user((u32)(u64)ka->sa.sa_handler, &sc->handler)
+ if (__put_user((u32)(u64)ka_copy->sa.sa_handler, &sc->handler)
|| __put_user(oldset->sig[0], &sc->oldmask)
|| __put_user((oldset->sig[0] >> 32), &sc->_unused[3])
|| __put_user((u32)(u64)frame, &sc->regs)
@@ -868,7 +868,7 @@
regs->gpr[1] = (unsigned long) newsp;
regs->gpr[3] = sig;
regs->gpr[4] = (unsigned long) sc;
- regs->nip = (unsigned long) ka->sa.sa_handler;
+ regs->nip = (unsigned long) ka_copy->sa.sa_handler;
regs->link = (unsigned long) frame->mctx.tramp;
regs->trap = 0;

@@ -880,7 +880,7 @@
regs, frame, *newspp);
#endif
if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
+ current->sighand->action[SIGSEGV-1].sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}

@@ -944,18 +944,16 @@
int do_signal32(sigset_t *oldset, struct pt_regs *regs)
{
siginfo_t info;
- struct k_sigaction *ka;
unsigned int frame, newsp;
int signr, ret;
+ struct k_sigaction ka_copy;

if (!oldset)
oldset = &current->blocked;

newsp = frame = 0;

- signr = get_signal_to_deliver(&info, regs, NULL);
-
- ka = (signr == 0)? NULL: &current->sighand->action[signr-1];
+ signr = get_signal_to_deliver(&info, &ka_copy, regs, NULL);

if (regs->trap == 0x0C00 /* System Call! */
&& regs->ccr & 0x10000000 /* error signalled */
@@ -966,7 +964,7 @@
if (signr > 0
&& (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
|| (ret == ERESTARTSYS
- && !(ka->sa.sa_flags & SA_RESTART)))) {
+ && !(ka_copy.sa.sa_flags & SA_RESTART)))) {
/* make the system call return an EINTR error */
regs->result = -EINTR;
regs->gpr[3] = EINTR;
@@ -985,7 +983,7 @@
if (signr == 0)
return 0; /* no signals delivered */

- if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
+ if ((ka_copy.sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
&& (!on_sig_stack(regs->gpr[1])))
newsp = (current->sas_ss_sp + current->sas_ss_size);
else
@@ -993,17 +991,15 @@
newsp &= ~0xfUL;

/* Whee! Actually deliver the signal. */
- if (ka->sa.sa_flags & SA_SIGINFO)
- handle_rt_signal32(signr, ka, &info, oldset, regs, newsp);
+ if (ka_copy.sa.sa_flags & SA_SIGINFO)
+ handle_rt_signal32(signr, &ka_copy, &info, oldset, regs, newsp);
else
- handle_signal32(signr, ka, &info, oldset, regs, newsp);
-
- if (ka->sa.sa_flags & SA_ONESHOT)
- ka->sa.sa_handler = SIG_DFL;
+ handle_signal32(signr, &ka_copy, &info, oldset, regs, newsp);

- if (!(ka->sa.sa_flags & SA_NODEFER)) {
+ if (!(ka_copy.sa.sa_flags & SA_NODEFER)) {
spin_lock_irq(&current->sighand->siglock);
- sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+ sigorsets(&current->blocked, &current->blocked,
+ &ka_copy.sa.sa_mask);
sigaddset(&current->blocked, signr);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
-
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