2004-11-12 23:56:33

by Jeff Dike

Subject: [PATCH 10/11] - UML - Don't delay segfaults

>From Bodo Stroesser - This one covers the fact, that the SIGSEGV
signal, which is created by force_sigsegv() in case of an error in
handle_signal(), is not delivered to the user immediately. In the
worst case it even could be masked if a sigprocmask() systemcall
follows immediately after return from kernel. The patch is relevant
for other architectures, too.

Signed-off-by: Jeff Dike <[email protected]>

Index: 2.6.9/arch/um/kernel/signal_kern.c
===================================================================
--- 2.6.9.orig/arch/um/kernel/signal_kern.c 2004-11-12 16:24:20.000000000 -0500
+++ 2.6.9/arch/um/kernel/signal_kern.c 2004-11-12 16:24:21.000000000 -0500
@@ -38,9 +38,9 @@
/*
* OK, we're invoking a handler
*/
-static void handle_signal(struct pt_regs *regs, unsigned long signr,
- struct k_sigaction *ka, siginfo_t *info,
- sigset_t *oldset)
+static int handle_signal(struct pt_regs *regs, unsigned long signr,
+ struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *oldset)
{
unsigned long sp;
int err;
@@ -94,23 +94,25 @@
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
+
+ return err;
}

static int kern_do_signal(struct pt_regs *regs, sigset_t *oldset)
{
struct k_sigaction ka_copy;
siginfo_t info;
- int sig;
+ int sig, handled_sig = 0;

- sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL);
- if(sig > 0){
+ while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
+ handled_sig = 1;
/* Whee! Actually deliver the signal. */
- handle_signal(regs, sig, &ka_copy, &info, oldset);
- return(1);
+ if(!handle_signal(regs, sig, &ka_copy, &info, oldset))
+ break;
}

/* Did we come from a system call? */
- if(PT_REGS_SYSCALL_NR(regs) >= 0){
+ if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
/* Restart the system call - no handlers present */
if(PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOHAND ||
PT_REGS_SYSCALL_RET(regs) == -ERESTARTSYS ||
@@ -134,7 +136,7 @@
if(current->ptrace & PT_DTRACE)
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(&current->thread.regs));
- return(0);
+ return(handled_sig);
}

int do_signal(void)