Messages in this thread Patch in this message | | | From | OGAWA Hirofumi <> | Subject | fat: Fix uninit-memory access for partial initialized inode | Date | Sat, 22 Feb 2020 03:12:38 +0900 |
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When got error at middle of reading inode, some fields in inode might be still not initialized. And then evict_inode path may access those fields via iput().
To fix, this makes sure that inode fields are initialized.
Reported-by: syzbot+9d82b8de2992579da5d0@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> --- fs/fat/inode.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)
diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 5f04c5c..686130f 100644 --- a/fs/fat/inode.c 2020-02-09 21:29:07.541357068 +0900 +++ b/fs/fat/inode.c 2020-02-22 02:15:20.451313122 +0900 @@ -749,6 +749,13 @@ static struct inode *fat_alloc_inode(str return NULL; init_rwsem(&ei->truncate_lock); + /* Zeroing to allow iput() even if partial initialized inode. */ + ei->mmu_private = 0; + ei->i_start = 0; + ei->i_logstart = 0; + ei->i_attrs = 0; + ei->i_pos = 0; + return &ei->vfs_inode; } @@ -1373,16 +1380,6 @@ 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); @@ -1843,13 +1840,11 @@ int fat_fill_super(struct super_block *s fat_inode = new_inode(sb); if (!fat_inode) goto out_fail; - 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); _
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