From f5361da1e60d54ec81346aee8e3d8baf1be0b762 Mon Sep 17 00:00:00 2001
From: Zhihao Cheng <chengzhihao1@huawei.com>
Date: Wed, 8 Mar 2023 11:26:43 +0800
Subject: [PATCH] ext4: zero i_disksize when initializing the bootloader inode
Git-commit: f5361da1e60d54ec81346aee8e3d8baf1be0b762
Patch-mainline: v6.3-rc2
References: bsc#1213013
If the boot loader inode has never been used before, the
EXT4_IOC_SWAP_BOOT inode will initialize it, including setting the
i_size to 0. However, if the "never before used" boot loader has a
non-zero i_size, then i_disksize will be non-zero, and the
inconsistency between i_size and i_disksize can trigger a kernel
Warning:
WARNING: CPU: 0 PID: 2580 at fs/ext4/file.c:319
CPU: 0 PID: 2580 Comm: bb Not tainted 6.3.0-rc1-00004-g703695902cfa
RIP: 0010:ext4_file_write_iter+0xbc7/0xd10
Call Trace:
vfs_write+0x3b1/0x5c0
ksys_write+0x77/0x160
__x64_sys_write+0x22/0x30
do_syscall_64+0x39/0x80
Reproducer: 1. create corrupted image and mount it:
mke2fs -t ext4 /tmp/foo.img 200
debugfs -wR "sif <5> size 25700" /tmp/foo.img
mount -t ext4 /tmp/foo.img /mnt
cd /mnt
echo 123 > file
2. Run the reproducer program:
posix_memalign(&buf, 1024, 1024)
fd = open("file", O_RDWR | O_DIRECT);
ioctl(fd, EXT4_IOC_SWAP_BOOT);
write(fd, buf, 1024);
Fix this by setting i_disksize as well as i_size to zero when
initiaizing the boot loader inode.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217159
Cc: stable@kernel.org
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20230308032643.641113-1-chengzhihao1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
---
fs/ext4/ioctl.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 2e8c34036313..cc17205f7f49 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -431,6 +431,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
ei_bl->i_flags = 0;
inode_set_iversion(inode_bl, 1);
i_size_write(inode_bl, 0);
+ EXT4_I(inode_bl)->i_disksize = inode_bl->i_size;
inode_bl->i_mode = S_IFREG;
if (ext4_has_feature_extents(sb)) {
ext4_set_inode_flag(inode_bl, EXT4_INODE_EXTENTS);
--
2.35.3