linux-ext4 - [PATCH 01/10] libext2fs: Fix possible inode count overflow when creating fs

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Date:   Tue, 12 Jun 2018 11:53:19 +0200
From:   Jan Kara <jack@...e.cz>
To:     <linux-ext4@...r.kernel.org>
Cc:     Ted Tso <tytso@....edu>, Jan Kara <jack@...e.cz>
Subject: [PATCH 01/10] libext2fs: Fix possible inode count overflow when creating fs

If blocks count is exactly 1<<32, then the code computing number of
inode count in ext2fs_initialize() will overflow and set number of
inodes to 0 (which will be later fixed up to EXT2_FIRST_INODE(super)+1).
Fix the off-by-one bug in the check.

Reviewed-by: Andreas Dilger <adilger@...ger.ca>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 lib/ext2fs/initialize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index dbe798b27826..e1eff22eac33 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -295,7 +295,7 @@ retry:
 	i = fs->blocksize >= 4096 ? 1 : 4096 / fs->blocksize;
 
 	if (ext2fs_has_feature_64bit(super) &&
-	    (ext2fs_blocks_count(super) / i) > (1ULL << 32))
+	    (ext2fs_blocks_count(super) / i) >= (1ULL << 32))
 		set_field(s_inodes_count, ~0U);
 	else
 		set_field(s_inodes_count, ext2fs_blocks_count(super) / i);
-- 
2.13.7