[PATCH] fs/btrfs: Integer overflow in btrfs_ioctl_resize()

[Wenliang Fan]

The local variable 'new_size' comes from userspace. If a large number
was passed, there would be an integer overflow in the following line:
	new_size = old_size + new_size;

Signed-off-by: Wenliang Fan <fanwlexca@xxxxxxxxx>
---
 fs/btrfs/ioctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 21da576..92f7707 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1466,6 +1466,10 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 		}
 		new_size = old_size - new_size;
 	} else if (mod > 0) {
+		if (new_size > ULLONG_MAX - old_size) {
+			ret = -EINVAL;
+			goto out_free;
+		}
 		new_size = old_size + new_size;
 	}
 
-- 
1.8.5.rc1.28.g7061504

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