From: "Darrick J. Wong" darrick.wong@oracle.com
mainline inclusion from mainline-5.4-rc1 commit 1638045c36772b47a0765f7dca07cb90267e4942 category: bugfix bugzilla: 50612 CVE: NA ---------------------------
Set S_SWAPFILE on block device inodes so that they have the same protections as a swap flie.
Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: zhangyi (F) yi.zhang@huawei.com Reviewed-by: yangerkun yangerkun@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- mm/swapfile.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c index 13171e764c56..06df64e59d9c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2474,9 +2474,8 @@ add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, * requirements, they are simply tossed out - we will never use those blocks * for swapping. * - * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This - * prevents root from shooting her foot off by ftruncating an in-use swapfile, - * which will scribble on the fs. + * For all swap devices we set S_SWAPFILE across the life of the swapon. This + * prevents users from writing to the swap device, which will corrupt memory. * * The amount of disk space which a single swap extent represents varies. * Typically it is in the 1-4 megabyte range. So we can have hundreds of @@ -2767,13 +2766,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) inode = mapping->host; if (S_ISBLK(inode->i_mode)) { struct block_device *bdev = I_BDEV(inode); + set_blocksize(bdev, old_block_size); blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); - } else { - inode_lock(inode); - inode->i_flags &= ~S_SWAPFILE; - inode_unlock(inode); } + + inode_lock(inode); + inode->i_flags &= ~S_SWAPFILE; + inode_unlock(inode); filp_close(swap_file, NULL);
/* @@ -2999,11 +2999,11 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) p->flags |= SWP_BLKDEV; } else if (S_ISREG(inode->i_mode)) { p->bdev = inode->i_sb->s_bdev; - inode_lock(inode); - if (IS_SWAPFILE(inode)) - return -EBUSY; - } else - return -EINVAL; + } + + inode_lock(inode); + if (IS_SWAPFILE(inode)) + return -EBUSY;
return 0; } @@ -3404,8 +3404,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) atomic_inc(&proc_poll_event); wake_up_interruptible(&proc_poll_wait);
- if (S_ISREG(inode->i_mode)) - inode->i_flags |= S_SWAPFILE; + inode->i_flags |= S_SWAPFILE; error = 0; goto out; bad_swap: @@ -3427,7 +3426,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (inced_nr_rotate_swap) atomic_dec(&nr_rotate_swap); if (swap_file) { - if (inode && S_ISREG(inode->i_mode)) { + if (inode) { inode_unlock(inode); inode = NULL; } @@ -3440,7 +3439,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) } if (name) putname(name); - if (inode && S_ISREG(inode->i_mode)) + if (inode) inode_unlock(inode); if (!error) enable_swap_slots_cache();