| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.11 297/329] xen/gntdev: fix gntdev_mmap() error exit path | Date | Mon, 17 May 2021 16:03:28 +0200 |
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From: Juergen Gross <jgross@suse.com>
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@vger.kernel.org Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Luca Fancellu <luca.fancellu@arm.com> Link: https://lore.kernel.org/r/20210423054038.26696-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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);
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