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/swapfile.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'mm/swapfile.c') diff --git a/mm/swapfile.c b/mm/swapfile.c index a53b7c49b40e..dab43523afdd 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3275,6 +3275,17 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (error) goto bad_swap; + /* + * Flush any pending IO and dirty mappings before we start using this + * swap device. + */ + inode->i_flags |= S_SWAPFILE; + error = inode_drain_writes(inode); + if (error) { + inode->i_flags &= ~S_SWAPFILE; + goto bad_swap; + } + mutex_lock(&swapon_mutex); prio = -1; if (swap_flags & SWAP_FLAG_PREFER) @@ -3295,7 +3306,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) atomic_inc(&proc_poll_event); wake_up_interruptible(&proc_poll_wait); - inode->i_flags |= S_SWAPFILE; error = 0; goto out; bad_swap: -- cgit