From: Domenico Andreoli <domenico.andreoli@xxxxxxxxx>
It turns out that there is one use case for programs being able to
write to swap devices, and that is the userspace hibernation code.
Quick fix: disable the S_SWAPFILE check if hibernation is configured.
Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
Reported-by: Domenico Andreoli <domenico.andreoli@xxxxxxxxx>
Reported-by: Marian Klein <mkleinsoft@xxxxxxxxx>
Signed-off-by: Domenico Andreoli <domenico.andreoli@xxxxxxxxx>
v2:
- use hibernation_available() instead of IS_ENABLED(CONFIG_HIBERNATE)
- make Fixes: point to the right commit
---
fs/block_dev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
Index: b/fs/block_dev.c
===================================================================
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -34,6 +34,7 @@
#include <linux/task_io_accounting_ops.h>
#include <linux/falloc.h>
#include <linux/uaccess.h>
+#include <linux/suspend.h>
#include "internal.h"
struct bdev_inode {
@@ -2001,7 +2002,8 @@ ssize_t blkdev_write_iter(struct kiocb *
if (bdev_read_only(I_BDEV(bd_inode)))
return -EPERM;
- if (IS_SWAPFILE(bd_inode))
+ /* uswsusp needs write permission to the swap */
+ if (IS_SWAPFILE(bd_inode) && !hibernation_available())
return -ETXTBSY;
if (!iov_iter_count(from))
