uprobes: Fix utask->xol_vaddr leak in pre_ssout()

pre_ssout() should do xol_free_insn_slot() if arch_uprobe_pre_xol()
fails, otherwise nobody will free the allocated slot.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 8d9c5bcb110e..0527379dac5b 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1306,6 +1306,7 @@ pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
 {
         struct uprobe_task *utask;
         unsigned long xol_vaddr;
+        int err;
 
         utask = current->utask;
 
@@ -1316,7 +1317,13 @@ pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
         utask->xol_vaddr = xol_vaddr;
         utask->vaddr = bp_vaddr;
 
-        return arch_uprobe_pre_xol(&uprobe->arch, regs);
+        err = arch_uprobe_pre_xol(&uprobe->arch, regs);
+        if (unlikely(err)) {
+                xol_free_insn_slot(current);
+                return err;
+        }
+
+        return 0;
 }
 
 /*