84d934195e
Signed-off-by: zhangqiumiao <zhangqiumiao1@huawei.com> (cherry picked from commit a498e6772ee1ecd064dedc063c5afef71710bbde)
81 lines
2.9 KiB
Diff
81 lines
2.9 KiB
Diff
From 25d64bb273c09d6346c0703b378f6e4f1d6d67c2 Mon Sep 17 00:00:00 2001
|
|
From: Daniel Drake <drake@endlessm.com>
|
|
Date: Fri, 12 Mar 2021 12:05:08 -0600
|
|
Subject: [PATCH] fs/minix: Avoid mistakenly probing ext2 filesystems
|
|
|
|
The ext2 (and ext3, ext4) filesystems write the number of free inodes to
|
|
location 0x410.
|
|
|
|
On a MINIX filesystem, that same location is used for the MINIX superblock
|
|
magic number.
|
|
|
|
If the number of free inodes on an ext2 filesystem is equal to any
|
|
of the four MINIX superblock magic values plus any multiple of 65536,
|
|
GRUB's MINIX filesystem code will probe it as a MINIX filesystem.
|
|
|
|
In the case of an OS using ext2 as the root filesystem, since there will
|
|
ordinarily be some amount of file creation and deletion on every bootup,
|
|
it effectively means that this situation has a 1:16384 chance of being hit
|
|
on every reboot.
|
|
|
|
This will cause GRUB's filesystem probing code to mistakenly identify an
|
|
ext2 filesystem as MINIX. This can be seen by e.g. "search --label"
|
|
incorrectly indicating that no such ext2 partition with matching label
|
|
exists, whereas in fact it does.
|
|
|
|
After spotting the rough cause of the issue I was facing here, I borrowed
|
|
much of the diagnosis/explanation from meierfra who found and investigated
|
|
the same issue in util-linux in 2010:
|
|
|
|
https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/518582
|
|
|
|
This was fixed in util-linux by having the MINIX code check for the
|
|
ext2 magic. Do the same here.
|
|
|
|
Signed-off-by: Daniel Drake <drake@endlessm.com>
|
|
Reviewed-by: Derek Foreman <derek@endlessos.org>
|
|
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
---
|
|
grub-core/fs/minix.c | 18 +++++++++++++++++-
|
|
1 file changed, 17 insertions(+), 1 deletion(-)
|
|
|
|
diff --git a/grub-core/fs/minix.c b/grub-core/fs/minix.c
|
|
index d0d08363c..3cd18c85b 100644
|
|
--- a/grub-core/fs/minix.c
|
|
+++ b/grub-core/fs/minix.c
|
|
@@ -38,6 +38,8 @@ GRUB_MOD_LICENSE ("GPLv3+");
|
|
#define GRUB_MINIX_MAGIC_30 0x138F
|
|
#endif
|
|
|
|
+#define EXT2_MAGIC 0xEF53
|
|
+
|
|
#define GRUB_MINIX_INODE_DIR_BLOCKS 7
|
|
#define GRUB_MINIX_LOG2_BSIZE 1
|
|
#define GRUB_MINIX_ROOT_INODE 1
|
|
@@ -466,7 +468,21 @@ grub_minix_find_file (struct grub_minix_data *data, const char *path)
|
|
static struct grub_minix_data *
|
|
grub_minix_mount (grub_disk_t disk)
|
|
{
|
|
- struct grub_minix_data *data;
|
|
+ struct grub_minix_data *data = NULL;
|
|
+ grub_uint16_t ext2_marker;
|
|
+
|
|
+ grub_disk_read (disk, 2, 56, sizeof (ext2_marker), &ext2_marker);
|
|
+ if (grub_errno != GRUB_ERR_NONE)
|
|
+ goto fail;
|
|
+
|
|
+ /*
|
|
+ * The ext2 filesystems can sometimes be mistakenly identified as MINIX, e.g.
|
|
+ * due to the number of free ext2 inodes being written to the same location
|
|
+ * where the MINIX superblock magic is found. Avoid such situations by
|
|
+ * skipping any filesystems that have the ext2 superblock magic.
|
|
+ */
|
|
+ if (ext2_marker == grub_cpu_to_le16_compile_time (EXT2_MAGIC))
|
|
+ goto fail;
|
|
|
|
data = grub_malloc (sizeof (struct grub_minix_data));
|
|
if (!data)
|
|
--
|
|
2.27.0
|
|
|