From fe8715e1337a1bad5c49e165ab77c033c334efbc Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Mon, 20 Jul 2020 20:51:08 +0800
Subject: [PATCH 1/2] btrfs-progs: convert: prevent 32bit overflow for
cctx->total_bytes
[BUG]
When convert is called on a 64GiB ext4 fs, it fails like this:
$ btrfs-convert /dev/loop0p1
create btrfs filesystem:
blocksize: 4096
nodesize: 16384
features: extref, skinny-metadata (default)
checksum: crc32c
creating ext2 image file
ERROR: missing data block for bytenr 1048576
ERROR: failed to create ext2_saved/image: -2
WARNING: an error occurred during conversion, filesystem is partially created but not finalized and not mountable
Btrfs-convert also corrupts the source fs:
$ LANG=C e2fsck /dev/loop0p1 -f
e2fsck 1.45.6 (20-Mar-2020)
Resize inode not valid. Recreate<y>? yes
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 3681 has zero dtime. Fix<y>? yes
Inodes that were part of a corrupted orphan linked list found. Fix<y>? yes
Inode 3744 was part of the orphaned inode list. FIXED.
Deleted inode 3745 has zero dtime. Fix<y>? yes
Inode 3747 has INLINE_DATA_FL flag on filesystem without inline data support.
Clear<y>? yes
...
[CAUSE]
After some debugging, the first strange behavior is, the value of
cctx->total_bytes is 0 in ext2_open_fs().
It turns out that, the value assign for cctx->total_bytes could lead to
bit overflow for the unsigned int value.
And that 0 cctx->total_bytes leads to various problems for later free
space calculation.
For example, in calculate_available_space(), we use cctx->total_bytes to
ensure we won't create a data chunk beyond device end:
cue_len = min(cctx->total_bytes - cur_off, cur_len);
If that cur_offset is also 0, we will create a cache_extent with 0 size,
which could cause a lot of problems for cache tree search.
[FIX]
Do manual casting for the multiply operation, so we could got a real u64
result. The fix will be applied to all supported fses (ext* and
reiserfs).
Reported-by: Christian Zangl <coralllama@gmail.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
(cherry picked from commit 670a19828ad40004d05ad70cdd45d58008d3fb51)
---
convert/main.c | 1 +
convert/source-ext2.c | 2 +-
convert/source-reiserfs.c | 2 +-
3 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/convert/main.c b/convert/main.c
index 7709e9a6..df6a2ae3 100644
--- a/convert/main.c
+++ b/convert/main.c
@@ -1136,6 +1136,7 @@ static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
if (ret)
goto fail;
+ ASSERT(cctx.total_bytes);
blocksize = cctx.blocksize;
total_bytes = (u64)blocksize * (u64)cctx.block_count;
if (blocksize < 4096) {
diff --git a/convert/source-ext2.c b/convert/source-ext2.c
index f11ef651..d73684ef 100644
--- a/convert/source-ext2.c
+++ b/convert/source-ext2.c
@@ -87,7 +87,7 @@ static int ext2_open_fs(struct btrfs_convert_context *cctx, const char *name)
cctx->fs_data = ext2_fs;
cctx->blocksize = ext2_fs->blocksize;
cctx->block_count = ext2_fs->super->s_blocks_count;
- cctx->total_bytes = ext2_fs->blocksize * ext2_fs->super->s_blocks_count;
+ cctx->total_bytes = (u64)ext2_fs->super->s_blocks_count * ext2_fs->blocksize;
cctx->volume_name = strndup((char *)ext2_fs->super->s_volume_name, 16);
cctx->first_data_block = ext2_fs->super->s_first_data_block;
cctx->inodes_count = ext2_fs->super->s_inodes_count;
diff --git a/convert/source-reiserfs.c b/convert/source-reiserfs.c
index 9fd6b9ab..3b4cb5ad 100644
--- a/convert/source-reiserfs.c
+++ b/convert/source-reiserfs.c
@@ -82,7 +82,7 @@ static int reiserfs_open_fs(struct btrfs_convert_context *cxt, const char *name)
cxt->fs_data = fs;
cxt->blocksize = fs->fs_blocksize;
cxt->block_count = get_sb_block_count(fs->fs_ondisk_sb);
- cxt->total_bytes = cxt->blocksize * cxt->block_count;
+ cxt->total_bytes = (u64)cxt->block_count * cxt->blocksize;
cxt->volume_name = strndup(fs->fs_ondisk_sb->s_label, 16);
cxt->first_data_block = 0;
cxt->inodes_count = reiserfs_count_objectids(fs);
--
2.26.2
