path: root/kernel
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authorMasoud Asgharifard Sharbiani <masouds@google.com>2007-07-22 11:12:28 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-22 11:03:37 -0700
commitabd4f7505bafdd6c5319fe3cb5caf9af6104e17a (patch)
treea543fce720331dbf6194a2c0471f36b7727b9736 /kernel
parent5fa63fccc579ac609fc7f86d29ccb3a2edf910d7 (diff)
x86: i386-show-unhandled-signals-v3
This patch makes the i386 behave the same way that x86_64 does when a segfault happens. A line gets printed to the kernel log so that tools that need to check for failures can behave more uniformly between debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 > /proc/sys/debug/exception-trace) Also, all of the lines being printed are now using printk_ratelimit() to deny the ability of DoS from a local user with a program like the following: main() { while (1) if (!fork()) *(int *)0 = 0; } This new revision also includes the fix that Andrew did which got rid of new sysctl that was added to the system in earlier versions of this. Also, 'show-unhandled-signals' sysctl has been renamed back to the old 'exception-trace' to avoid breakage of people's scripts. AK: Enabling by default for i386 will be likely controversal, but let's see what happens AK: Really folks, before complaining just fix your segfaults AK: I bet this will find a lot of silent issues Signed-off-by: Masoud Sharbiani <masouds@google.com> Signed-off-by: Andi Kleen <ak@suse.de> [ Personally, I've found the complaints useful on x86-64, so I'm all for this. That said, I wonder if we could do it more prettily.. -Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
2 files changed, 20 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 39d122753ba..ef8156a6aad 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -255,6 +255,16 @@ flush_signal_handlers(struct task_struct *t, int force_default)
+int unhandled_signal(struct task_struct *tsk, int sig)
+ if (is_init(tsk))
+ return 1;
+ if (tsk->ptrace & PT_PTRACED)
+ return 0;
+ return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
+ (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
/* Notify the system that a driver wants to block all signals for this
* process, and wants to be notified if any signals at all were to be
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 222299844ad..ddebf3f2aff 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1203,6 +1203,16 @@ static ctl_table fs_table[] = {
static ctl_table debug_table[] = {
+#ifdef CONFIG_X86
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "exception-trace",
+ .data = &show_unhandled_signals,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
{ .ctl_name = 0 }