From dc617f29dbe5ef0c8ced65ce62c464af1daaab3d Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Tue, 20 Aug 2019 07:55:16 -0700 Subject: vfs: don't allow writes to swap files Don't let userspace write to an active swap file because the kernel effectively has a long term lease on the storage and things could get seriously corrupted if we let this happen. Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- mm/mmap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 7e8c3e8ae75f..6bc21fca20bc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1483,8 +1483,12 @@ unsigned long do_mmap(struct file *file, unsigned long addr, case MAP_SHARED_VALIDATE: if (flags & ~flags_mask) return -EOPNOTSUPP; - if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) - return -EACCES; + if (prot & PROT_WRITE) { + if (!(file->f_mode & FMODE_WRITE)) + return -EACCES; + if (IS_SWAPFILE(file->f_mapping->host)) + return -ETXTBSY; + } /* * Make sure we don't allow writing to an append-only -- cgit v1.2.3