From: Juergen Gross <jgross@xxxxxxxx>
commit 970655aa9b42461f8394e4457307005bdeee14d9 upstream.
Commit d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
introduced an error in gntdev_mmap(): in case the call of
mmu_interval_notifier_insert_locked() fails the exit path should not
call mmu_interval_notifier_remove(), as this might result in NULL
dereferences.
One reason for failure is e.g. a signal pending for the running
process.
Fixes: d3eeb1d77c5d0af ("xen/gntdev: use mmu_interval_notifier_insert")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Link: https://lore.kernel.org/r/20210423054038.26696-1-jgross@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/gntdev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1005,8 +1005,10 @@ static int gntdev_mmap(struct file *flip
err = mmu_interval_notifier_insert_locked(
&map->notifier, vma->vm_mm, vma->vm_start,
vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
- if (err)
+ if (err) {
+ map->vma = NULL;
goto out_unlock_put;
+ }
}
mutex_unlock(&priv->lock);
