From 7c1def1652c6c1a95eafca2991baace34afaed0f Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Thu, 23 Jun 2005 00:08:21 -0700 Subject: [PATCH] [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/signal.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c index ea46d028af08..344400787c39 100644 --- a/arch/i386/kernel/signal.c +++ b/arch/i386/kernel/signal.c @@ -346,8 +346,8 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) extern void __user __kernel_sigreturn; extern void __user __kernel_rt_sigreturn; -static void setup_frame(int sig, struct k_sigaction *ka, - sigset_t *set, struct pt_regs * regs) +static int setup_frame(int sig, struct k_sigaction *ka, + sigset_t *set, struct pt_regs * regs) { void __user *restorer; struct sigframe __user *frame; @@ -429,13 +429,14 @@ static void setup_frame(int sig, struct k_sigaction *ka, current->comm, current->pid, frame, regs->eip, frame->pretcode); #endif - return; + return 1; give_sigsegv: force_sigsegv(sig, current); + return 0; } -static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, +static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs * regs) { void __user *restorer; @@ -522,20 +523,23 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, current->comm, current->pid, frame, regs->eip, frame->pretcode); #endif - return; + return 1; give_sigsegv: force_sigsegv(sig, current); + return 0; } /* * OK, we're invoking a handler */ -static void +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.. */ @@ -569,17 +573,19 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, /* Set up the stack frame */ if (ka->sa.sa_flags & SA_SIGINFO) - setup_rt_frame(sig, ka, info, oldset, regs); + ret = setup_rt_frame(sig, ka, info, oldset, regs); else - setup_frame(sig, ka, oldset, regs); + ret = setup_frame(sig, ka, oldset, regs); - if (!(ka->sa.sa_flags & SA_NODEFER)) { + if (ret && !(ka->sa.sa_flags & SA_NODEFER)) { spin_lock_irq(¤t->sighand->siglock); sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); sigaddset(¤t->blocked,sig); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); } + + return ret; } /* @@ -622,8 +628,7 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset) } /* Whee! Actually deliver the signal. */ - handle_signal(signr, &info, &ka, oldset, regs); - return 1; + return handle_signal(signr, &info, &ka, oldset, regs); } no_signal: -- 2.30.2