2020-07-22 01:26:14

by Hongxu Jia

[permalink] [raw]
Subject: [PATCH] mke2fs: fix up check for hardlinks always false if inode > 0xFFFFFFFF

While file has a large inode number (> 0xFFFFFFFF), mkfs.ext4 could
not parse hardlink correctly.

Prepare three hardlink files for mkfs.ext4

$ ls -il rootfs_ota/a rootfs_ota/boot/b rootfs_ota/boot/c
11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/a
11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/boot/b
11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/boot/c

$ truncate -s 1M rootfs_ota.ext4

$ mkfs.ext4 -F -i 8192 rootfs_ota.ext4 -L otaroot -U fd5f8768-c779-4dc9-adde-165a3d863349 -d rootfs_ota

$ mkdir mnt && sudo mount rootfs_ota.ext4 mnt

$ ls -il mnt/a mnt/boot/b mnt/boot/c
12 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/a
14 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/boot/b
15 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/boot/c

After applying this fix
$ ls -il mnt/a mnt/boot/b mnt/boot/c
12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/a
12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/boot/b
12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/boot/c

Since commit [382ed4a1 e2fsck: use proper types for variables][1]
applied, it used ext2_ino_t instead of ino_t for referencing inode
numbers, but the type of is_hardlink's `ino' should not be instead,
The ext2_ino_t is 32bit, if inode > 0xFFFFFFFF, its value will be
truncated.

Add a debug printf to show the value of inode, when it check for hardlink
files, it will always return false if inode > 0xFFFFFFFF
|--- a/misc/create_inode.c
|+++ b/misc/create_inode.c
|@@ -605,6 +605,7 @@ static int is_hardlink(struct hdlinks_s *hdlinks, dev_t dev, ext2_ino_t ino)
| {
| int i;
|
|+ printf("%s %d, %lX, %lX\n", __FUNCTION__, __LINE__, hdlinks->hdl[i].src_ino, ino);
| for (i = 0; i < hdlinks->count; i++) {
| if (hdlinks->hdl[i].src_dev == dev &&
| hdlinks->hdl[i].src_ino == ino)

Here is debug message:
is_hardlink 608, 2913DB886, 913DB886

The length of ext2_ino_t is 32bit (typedef __u32 __bitwise ext2_ino_t;),
and ino_t is 64bit on 64bit system (such as x86-64), recover `ino' to ino_t.

[1] https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?id=382ed4a1c2b60acb9db7631e86dda207bde6076e

Signed-off-by: Hongxu Jia <[email protected]>
---
misc/create_inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/misc/create_inode.c b/misc/create_inode.c
index e8d1df6b..837f3875 100644
--- a/misc/create_inode.c
+++ b/misc/create_inode.c
@@ -601,7 +601,7 @@ out:
return err;
}

-static int is_hardlink(struct hdlinks_s *hdlinks, dev_t dev, ext2_ino_t ino)
+static int is_hardlink(struct hdlinks_s *hdlinks, dev_t dev, ino_t ino)
{
int i;

--
2.21.0


2020-10-01 16:54:30

by Theodore Ts'o

[permalink] [raw]
Subject: Re: [PATCH] mke2fs: fix up check for hardlinks always false if inode > 0xFFFFFFFF

On Tue, Jul 21, 2020 at 06:25:03PM -0700, Hongxu Jia wrote:
> While file has a large inode number (> 0xFFFFFFFF), mkfs.ext4 could
> not parse hardlink correctly.
>
> Prepare three hardlink files for mkfs.ext4
>
> $ ls -il rootfs_ota/a rootfs_ota/boot/b rootfs_ota/boot/c
> 11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/a
> 11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/boot/b
> 11026675846 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 rootfs_ota/boot/c
>
> $ truncate -s 1M rootfs_ota.ext4
>
> $ mkfs.ext4 -F -i 8192 rootfs_ota.ext4 -L otaroot -U fd5f8768-c779-4dc9-adde-165a3d863349 -d rootfs_ota
>
> $ mkdir mnt && sudo mount rootfs_ota.ext4 mnt
>
> $ ls -il mnt/a mnt/boot/b mnt/boot/c
> 12 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/a
> 14 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/boot/b
> 15 -rw-r--r-- 1 hjia users 0 Jul 20 17:44 mnt/boot/c
>
> After applying this fix
> $ ls -il mnt/a mnt/boot/b mnt/boot/c
> 12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/a
> 12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/boot/b
> 12 -rw-r--r-- 3 hjia users 0 Jul 20 17:44 mnt/boot/c
>
> Since commit [382ed4a1 e2fsck: use proper types for variables][1]
> applied, it used ext2_ino_t instead of ino_t for referencing inode
> numbers, but the type of is_hardlink's `ino' should not be instead,
> The ext2_ino_t is 32bit, if inode > 0xFFFFFFFF, its value will be
> truncated.
>
> Add a debug printf to show the value of inode, when it check for hardlink
> files, it will always return false if inode > 0xFFFFFFFF
> |--- a/misc/create_inode.c
> |+++ b/misc/create_inode.c
> |@@ -605,6 +605,7 @@ static int is_hardlink(struct hdlinks_s *hdlinks, dev_t dev, ext2_ino_t ino)
> | {
> | int i;
> |
> |+ printf("%s %d, %lX, %lX\n", __FUNCTION__, __LINE__, hdlinks->hdl[i].src_ino, ino);
> | for (i = 0; i < hdlinks->count; i++) {
> | if (hdlinks->hdl[i].src_dev == dev &&
> | hdlinks->hdl[i].src_ino == ino)
>
> Here is debug message:
> is_hardlink 608, 2913DB886, 913DB886
>
> The length of ext2_ino_t is 32bit (typedef __u32 __bitwise ext2_ino_t;),
> and ino_t is 64bit on 64bit system (such as x86-64), recover `ino' to ino_t.
>
> [1] https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?id=382ed4a1c2b60acb9db7631e86dda207bde6076e
>
> Signed-off-by: Hongxu Jia <[email protected]>

Applied, thanks.

- Ted