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(-)
From: yangerkun yangerkun@huawei.com
hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8UB3F
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Buffer with verified means that it has been checked before. No need verify and call set_buffer_verified again.
Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Baokun Li libaokun1@huawei.com --- fs/ext4/extents.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 4d8496d1a8ac..3e4454987be5 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -568,13 +568,16 @@ __read_extent_tree_block(const char *function, unsigned int line, if (err < 0) goto errout; } - if (buffer_verified(bh) && !(flags & EXT4_EX_FORCE_CACHE)) - return bh; - err = __ext4_ext_check(function, line, inode, ext_block_hdr(bh), - depth, pblk, le32_to_cpu(idx->ei_block)); - if (err) - goto errout; - set_buffer_verified(bh); + if (buffer_verified(bh)) { + if (!(flags & EXT4_EX_FORCE_CACHE)) + return bh; + } else { + err = __ext4_ext_check(function, line, inode, ext_block_hdr(bh), + depth, pblk, le32_to_cpu(idx->ei_block)); + if (err) + goto errout; + set_buffer_verified(bh); + } /* * If this is a leaf block, cache all of its entries */
From: yangerkun yangerkun@huawei.com
hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8UB3F
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Our stress testing with IO error can trigger follow OOB with a very low probability.
[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
Digging deep and we found it's actually a xattr block which can happened with follow steps:
1. extent update for file1 and will remove a leaf extent block(block A) 2. we need update the idx extent block too 3. block A has been allocated as a xattr block and will set verified 3. io error happened for this idx block and will the buffer has been released late 4. extent find for file1 will read the idx block and see block A again 5. since the buffer of block A is already verified, we will use it directly, which can lead the upper OOB
Same as __ext4_xattr_check_block, we can check magic even the buffer is verified to fix the problem.
Signed-off-by: yangerkun yangerkun@huawei.com Signed-off-by: Baokun Li libaokun1@huawei.com --- fs/ext4/extents.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 3e4454987be5..7a97b032b45c 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -569,6 +569,14 @@ __read_extent_tree_block(const char *function, unsigned int line, goto errout; } if (buffer_verified(bh)) { + if (unlikely(ext_block_hdr(bh)->eh_magic != EXT4_EXT_MAGIC)) { + err = -EFSCORRUPTED; + ext4_error_inode(inode, function, line, 0, + "invalid magic for verified extent block %llu", + (unsigned long long)bh->b_blocknr); + goto errout; + } + if (!(flags & EXT4_EX_FORCE_CACHE)) return bh; } else {
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