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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2015-11-16 18:44:11 +0300
committerMiklos Szeredi <miklos@szeredi.hu>2015-12-11 16:30:49 +0100
commit84889d49335627bc770b32787c1ef9ebad1da232 (patch)
tree00f6932ed900339a13732ddd159c8d5110addbdf
parentcf9a6784f7c1b5ee2b9159a1246e327c331c5697 (diff)
downloadlinux-84889d49335627bc770b32787c1ef9ebad1da232.tar.bz2
ovl: check dentry positiveness in ovl_cleanup_whiteouts()
This patch fixes kernel crash at removing directory which contains whiteouts from lower layers. Cache of directory content passed as "list" contains entries from all layers, including whiteouts from lower layers. So, lookup in upper dir (moved into work at this stage) will return negative entry. Plus this cache is filled long before and we can race with external removal. Example: mkdir -p lower0/dir lower1/dir upper work overlay touch lower0/dir/a lower0/dir/b mknod lower1/dir/a c 0 0 mount -t overlay none overlay -o lowerdir=lower1:lower0,upperdir=upper,workdir=work rm -fr overlay/dir Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Cc: <stable@vger.kernel.org> # 3.18+
-rw-r--r--fs/overlayfs/readdir.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 70e9af551600..adcb1398c481 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -571,7 +571,8 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
(int) PTR_ERR(dentry));
continue;
}
- ovl_cleanup(upper->d_inode, dentry);
+ if (dentry->d_inode)
+ ovl_cleanup(upper->d_inode, dentry);
dput(dentry);
}
mutex_unlock(&upper->d_inode->i_mutex);