4.16-stable review patch. If anyone has any objections, please let me know.
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From: Jan Kara jack@suse.cz
commit 4f2f76f751433908364ccff82f437a57d0e6e9b7 upstream.
ext4_resize_fs() has an off-by-one bug when checking whether growing of a filesystem will not overflow inode count. As a result it allows a filesystem with 8192 inodes per group to grow to 64TB which overflows inode count to 0 and makes filesystem unusable. Fix it.
Cc: stable@vger.kernel.org Fixes: 3f8a6411fbada1fa482276591e037f3b1adcf55b Reported-by: Jaco Kroon jaco@uls.co.za Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Theodore Ts'o tytso@mit.edu Reviewed-by: Andreas Dilger adilger@dilger.ca Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext4/resize.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1933,7 +1933,7 @@ retry: return 0;
n_group = ext4_get_group_number(sb, n_blocks_count - 1); - if (n_group > (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) { + if (n_group >= (0xFFFFFFFFUL / EXT4_INODES_PER_GROUP(sb))) { ext4_warning(sb, "resize would cause inodes_count overflow"); return -EINVAL; }