From: Domenico Andreoli domenico.andreoli@linux.com
mainline inclusion from mainline-5.7-rc1 commit 56939e014a6c212b317414faa307029e2e80c3b9 category: bugfix bugzilla: 50612 CVE: NA ---------------------------
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@linux.com Reported-by: Marian Klein mkleinsoft@gmail.com Signed-off-by: Domenico Andreoli domenico.andreoli@linux.com Reviewed-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Signed-off-by: zhangyi (F) yi.zhang@huawei.com Reviewed-by: Yang Erkun yangerkun@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- fs/block_dev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c index 5f58e1a604a0..a90bfc36c6da 100644 --- 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 { @@ -2007,7 +2008,8 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) 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))