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authorZheng Liang <zhengliang6@huawei.com>2021-09-24 09:16:27 +0800
committerMiklos Szeredi <mszeredi@redhat.com>2021-09-24 21:00:31 +0200
commita295aef603e109a47af355477326bd41151765b6 (patch)
tree6c51213e683f2e13c04ec7ff7348695e86568fc4 /fs/overlayfs/file.c
parent6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f (diff)
ovl: fix missing negative dentry check in ovl_rename()
The following reproducer mkdir lower upper work merge touch lower/old touch lower/new mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge rm merge/new mv merge/old merge/new & unlink upper/new may result in this race: PROCESS A: rename("merge/old", "merge/new"); overwrite=true,ovl_lower_positive(old)=true, ovl_dentry_is_whiteout(new)=true -> flags |= RENAME_EXCHANGE PROCESS B: unlink("upper/new"); PROCESS A: lookup newdentry in new_upperdir call vfs_rename() with negative newdentry and RENAME_EXCHANGE Fix by adding the missing check for negative newdentry. Signed-off-by: Zheng Liang <zhengliang6@huawei.com> Fixes: e9be9d5e76e3 ("overlay filesystem") Cc: <stable@vger.kernel.org> # v3.18 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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