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authorOleg Nesterov <oleg@redhat.com>2014-04-03 20:20:10 +0200
committerOleg Nesterov <oleg@redhat.com>2014-04-17 21:58:20 +0200
commit014940bad8e46ca7bd0483f760f9cba60088a3d4 (patch)
treecbefdeb0f0d2b84f7609313f28fdf460c42dfaac /arch/x86/kernel/uprobes.c
parente55848a4f8ee52465771983e144f0c3337776eda (diff)
uprobes/x86: Send SIGILL if arch_uprobe_post_xol() fails
Currently the error from arch_uprobe_post_xol() is silently ignored. This doesn't look good and this can lead to the hard-to-debug problems. 1. Change handle_singlestep() to loudly complain and send SIGILL. Note: this only affects x86, ppc/arm can't fail. 2. Change arch_uprobe_post_xol() to call arch_uprobe_abort_xol() and avoid TF games if it is going to return an error. This can help to to analyze the problem, if nothing else we should not report ->ip = xol_slot in the core-file. Note: this means that handle_riprel_post_xol() can be called twice, but this is fine because it is idempotent. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Diffstat (limited to 'arch/x86/kernel/uprobes.c')
-rw-r--r--arch/x86/kernel/uprobes.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 08cdb82815fe..e72903eacd43 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -594,6 +594,15 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
struct uprobe_task *utask = current->utask;
WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+
+ if (auprobe->ops->post_xol) {
+ int err = auprobe->ops->post_xol(auprobe, regs);
+ if (err) {
+ arch_uprobe_abort_xol(auprobe, regs);
+ return err;
+ }
+ }
+
current->thread.trap_nr = utask->autask.saved_trap_nr;
/*
* arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
@@ -605,8 +614,6 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
else if (!(auprobe->fixups & UPROBE_FIX_SETF))
regs->flags &= ~X86_EFLAGS_TF;
- if (auprobe->ops->post_xol)
- return auprobe->ops->post_xol(auprobe, regs);
return 0;
}
@@ -641,8 +648,9 @@ int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
/*
* This function gets called when XOL instruction either gets trapped or
- * the thread has a fatal signal, so reset the instruction pointer to its
- * probed address.
+ * the thread has a fatal signal, or if arch_uprobe_post_xol() failed.
+ * Reset the instruction pointer to its probed address for the potential
+ * restart or for post mortem analysis.
*/
void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{