lkml.org 
[lkml]   [2021]   [Nov]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v3 01/12] ubifs: rename_whiteout: Fix double free for whiteout_ui->data
    Date
    'whiteout_ui->data' will be freed twice if space budget fail for
    rename whiteout operation as following process:

    rename_whiteout
    dev = kmalloc
    whiteout_ui->data = dev
    kfree(whiteout_ui->data) // Free first time
    iput(whiteout)
    ubifs_free_inode
    kfree(ui->data) // Double free!

    KASAN reports:
    ==================================================================
    BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70
    Call Trace:
    kfree+0x117/0x490
    ubifs_free_inode+0x4f/0x70 [ubifs]
    i_callback+0x30/0x60
    rcu_do_batch+0x366/0xac0
    __do_softirq+0x133/0x57f

    Allocated by task 1506:
    kmem_cache_alloc_trace+0x3c2/0x7a0
    do_rename+0x9b7/0x1150 [ubifs]
    ubifs_rename+0x106/0x1f0 [ubifs]
    do_syscall_64+0x35/0x80

    Freed by task 1506:
    kfree+0x117/0x490
    do_rename.cold+0x53/0x8a [ubifs]
    ubifs_rename+0x106/0x1f0 [ubifs]
    do_syscall_64+0x35/0x80

    The buggy address belongs to the object at ffff88810238bed8 which
    belongs to the cache kmalloc-8 of size 8
    ==================================================================

    Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused
    assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode()
    -> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it
    (because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release',
    and the nlink of whiteout inode is 0).

    Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
    Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
    ---
    fs/ubifs/dir.c | 2 --
    1 file changed, 2 deletions(-)

    diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
    index 7c61d0ec0159..cfa8881d8cca 100644
    --- a/fs/ubifs/dir.c
    +++ b/fs/ubifs/dir.c
    @@ -1425,8 +1425,6 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,

    err = ubifs_budget_space(c, &wht_req);
    if (err) {
    - kfree(whiteout_ui->data);
    - whiteout_ui->data_len = 0;
    iput(whiteout);
    goto out_release;
    }
    --
    2.31.1
    \
     
     \ /
      Last update: 2021-11-12 13:06    [W:3.474 / U:0.136 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site