4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: John Blackwood <john.blackwood@xxxxxxxx>
commit 5db4fd8c52810bd9740c1240ebf89223b171aa70 upstream.
Make sure to clear out any ptrace singlestep state when a ptrace(2)
PTRACE_DETACH call is made on arm64 systems.
Otherwise, the previously ptraced task will die off with a SIGTRAP
signal if the debugger just previously singlestepped the ptraced task.
Signed-off-by: John Blackwood <john.blackwood@xxxxxxxx>
[will: added comment to justify why this is in the arch code]
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/ptrace.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -58,6 +58,12 @@
*/
void ptrace_disable(struct task_struct *child)
{
+ /*
+ * This would be better off in core code, but PTRACE_DETACH has
+ * grown its fair share of arch-specific worts and changing it
+ * is likely to cause regressions on obscure architectures.
+ */
+ user_disable_single_step(child);
}
#ifdef CONFIG_HAVE_HW_BREAKPOINT
--
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