linux-ext4 - [PATCH 0/2] bugfix for read_extent_tree

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Date:   Sat, 4 Sep 2021 12:49:44 +0800
From:   yangerkun <yangerkun@...wei.com>
To:     <tytso@....edu>, <jack@...e.cz>
CC:     <linux-ext4@...r.kernel.org>, <yangerkun@...wei.com>,
        <yukuai3@...wei.com>
Subject: [PATCH 0/2] bugfix for read_extent_tree_block

Our stress testcase with io error can trigger later OOB:

    [59898.282466] BUG: KASAN: slab-out-of-bounds in ext4_find_extent+0x2e4/0x480
    ...
    [59898.287162] Call Trace:
    [59898.287575]  dump_stack+0x8b/0xb9
    [59898.288070]  print_address_description+0x73/0x280
    [59898.289903]  ext4_find_extent+0x2e4/0x480
    [59898.290553]  ext4_ext_map_blocks+0x125/0x1470
    [59898.295481]  ext4_map_blocks+0x5ee/0x940
    [59898.315984]  ext4_mpage_readpages+0x63c/0xdb0
    [59898.320231]  read_pages+0xe6/0x370
    [59898.321589]  __do_page_cache_readahead+0x233/0x2a0
    [59898.321594]  ondemand_readahead+0x157/0x450
    [59898.321598]  generic_file_read_iter+0xcb2/0x1550
    [59898.328828]  __vfs_read+0x233/0x360
    [59898.328840]  vfs_read+0xa5/0x190
    [59898.330126]  ksys_read+0xa5/0x150
    [59898.331405]  do_syscall_64+0x6d/0x1f0
    [59898.331418]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

It seem that a xattr block with verified confuse read_extent_tree_block.

The detail of the patch show us how to fix it.

yangerkun (2):
  ext4: avoid recheck extent for EXT4_EX_FORCE_CACHE
  ext4: check magic even the extent block bh is verified

 fs/ext4/extents.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

-- 
2.31.1