exportfs: do not read dentry after free
[ Upstream commit 2084ac6c50
]
The function dentry_connected calls dput(dentry) to drop the previously
acquired reference to dentry. In this case, dentry can be released.
After that, IS_ROOT(dentry) checks the condition
(dentry == dentry->d_parent), which may result in a use-after-free bug.
This patch directly compares dentry with its parent obtained before
dropping the reference.
Fixes: a056cc8934c("exportfs: stop retrying once we race with
rename/remove")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -77,7 +77,7 @@ static bool dentry_connected(struct dentry *dentry)
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struct dentry *parent = dget_parent(dentry);
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dput(dentry);
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if (IS_ROOT(dentry)) {
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if (dentry == parent) {
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dput(parent);
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return false;
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}
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