From: Eryu Guan Date: Fri, 22 Feb 2013 20:27:47 +0000 (-0500) Subject: ext4: no need to remove extent if len is 0 in ext4_es_remove_extent() X-Git-Tag: v3.9-rc1~64^2~1 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d43814721111041e26671a153e300e2054fb36fa;p=karo-tx-linux.git ext4: no need to remove extent if len is 0 in ext4_es_remove_extent() len is 0 means no extent needs to be removed, so return immediately. Otherwise it could trigger the following BUG_ON() in ext4_es_remove_extent() end = lblk + len - 1; BUG_ON(end < lblk); This could be reproduced by a simple truncate(1) command by an unprivileged user truncate -s $(($((2**32 - 1)) * 4096)) /mnt/ext4/testfile The same is true for __es_insert_extent(). Patched kernel passed xfstests regression test. Signed-off-by: Eryu Guan Signed-off-by: "Theodore Ts'o" Reviewed-by: Zheng Liu --- diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c index 9f1380e05474..f768f4a98a2b 100644 --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -456,6 +456,9 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk, es_debug("add [%u/%u) %llu %llx to extent status tree of inode %lu\n", lblk, len, pblk, status, inode->i_ino); + if (!len) + return 0; + BUG_ON(end < lblk); newes.es_lblk = lblk; @@ -649,6 +652,9 @@ int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk, es_debug("remove [%u/%u) from extent status tree of inode %lu\n", lblk, len, inode->i_ino); + if (!len) + return err; + end = lblk + len - 1; BUG_ON(end < lblk);