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ovl: fix use inode directly in rcu-walk mode
commit672e4268b2
upstream. ovl_dentry_revalidate_common() can be called in rcu-walk mode. As document said, "in rcu-walk mode, d_parent and d_inode should not be used without care". Check inode here to protect access under rcu-walk mode. Fixes:bccece1ead
("ovl: allow remote upper") Reported-and-tested-by: syzbot+a4055c78774bbf3498bb@syzkaller.appspotmail.com Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com> Cc: <stable@vger.kernel.org> # v5.7 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 6 additions and 1 deletions
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@ -139,11 +139,16 @@ static int ovl_dentry_revalidate_common(struct dentry *dentry,
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unsigned int flags, bool weak)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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struct inode *inode = d_inode_rcu(dentry);
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struct dentry *upper;
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unsigned int i;
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int ret = 1;
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upper = ovl_dentry_upper(dentry);
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/* Careful in RCU mode */
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if (!inode)
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return -ECHILD;
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upper = ovl_i_dentry_upper(inode);
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if (upper)
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ret = ovl_revalidate_real(upper, flags, weak);
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