Recently fallocate patch was merged and it uses
MSDOS_I(inode)->mmu_private at fat_evict_inode(). However,
fat_inode/fsinfo_inode that was introduced in past didn't initialize
MSDOS_I(inode) properly.
With those combinations, it became the cause of accessing random entry
in FAT area.
Reported-by: Moreno Bartalucci <moreno.bartalucci@xxxxxxxxxxxx>
Tested-by: Moreno Bartalucci <moreno.bartalucci@xxxxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
---
fs/fat/inode.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff -puN fs/fat/inode.c~fat-fix-fsinfo_inode fs/fat/inode.c
--- linux/fs/fat/inode.c~fat-fix-fsinfo_inode 2017-03-07 12:34:54.507838051 +0900
+++ linux-hirofumi/fs/fat/inode.c 2017-03-08 03:48:37.877751531 +0900
@@ -1359,6 +1359,16 @@ out:
return 0;
}
+static void fat_dummy_inode_init(struct inode *inode)
+{
+ /* Initialize this dummy inode to work as no-op. */
+ MSDOS_I(inode)->mmu_private = 0;
+ MSDOS_I(inode)->i_start = 0;
+ MSDOS_I(inode)->i_logstart = 0;
+ MSDOS_I(inode)->i_attrs = 0;
+ MSDOS_I(inode)->i_pos = 0;
+}
+
static int fat_read_root(struct inode *inode)
{
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
@@ -1803,12 +1813,13 @@ int fat_fill_super(struct super_block *s
fat_inode = new_inode(sb);
if (!fat_inode)
goto out_fail;
- MSDOS_I(fat_inode)->i_pos = 0;
+ fat_dummy_inode_init(fat_inode);
sbi->fat_inode = fat_inode;
fsinfo_inode = new_inode(sb);
if (!fsinfo_inode)
goto out_fail;
+ fat_dummy_inode_init(fsinfo_inode);
fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
sbi->fsinfo_inode = fsinfo_inode;
insert_inode_hash(fsinfo_inode);
_
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
