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authorDarrick J. Wong <darrick.wong@oracle.com>2019-08-20 07:55:16 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-08-20 07:55:16 -0700
commitdc617f29dbe5ef0c8ced65ce62c464af1daaab3d (patch)
tree3596eb0d334f04f87088c735748bba8e66a71cad /mm/mmap.c
parent1638045c36772b47a0765f7dca07cb90267e4942 (diff)
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 <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c8
1 files changed, 6 insertions, 2 deletions
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