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authorTheodore Ts'o <tytso@mit.edu>2018-08-27 01:47:09 -0400
committerTheodore Ts'o <tytso@mit.edu>2018-08-27 01:47:09 -0400
commitb50282f3241acee880514212d88b6049fb5039c8 (patch)
treeb848cc5a2dce967053f7e1c63ee782e619100b07 /fs/ext4/namei.c
parent072ebb3bffe67d71d1f1e52add799f4491eab691 (diff)
downloadlinux-stericsson-b50282f3241acee880514212d88b6049fb5039c8.tar.gz
ext4: check to make sure the rename(2)'s destination is not freed
If the destination of the rename(2) system call exists, the inode's link count (i_nlinks) must be non-zero. If it is, the inode can end up on the orphan list prematurely, leading to all sorts of hilarity, including a use-after-free. https://bugzilla.kernel.org/show_bug.cgi?id=200931 Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported-by: Wen Xu <wen.xu@gatech.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/namei.c')
-rw-r--r--fs/ext4/namei.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 116ff68c5bd4..377d516c475f 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3478,6 +3478,12 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
int credits;
u8 old_file_type;
+ if (new.inode && new.inode->i_nlink == 0) {
+ EXT4_ERROR_INODE(new.inode,
+ "target of rename is already freed");
+ return -EFSCORRUPTED;
+ }
+
if ((ext4_test_inode_flag(new_dir, EXT4_INODE_PROJINHERIT)) &&
(!projid_eq(EXT4_I(new_dir)->i_projid,
EXT4_I(old_dentry->d_inode)->i_projid)))