Messages in this thread Patch in this message | | | From | Pan Bian <> | Subject | [PATCH] exportfs: do not read dentry after free | Date | Fri, 23 Nov 2018 11:15:53 +0800 |
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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> --- fs/exportfs/expfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c index 645158d..a69aaf5 100644 --- a/fs/exportfs/expfs.c +++ b/fs/exportfs/expfs.c @@ -77,7 +77,7 @@ static bool dentry_connected(struct dentry *dentry) struct dentry *parent = dget_parent(dentry); dput(dentry); - if (IS_ROOT(dentry)) { + if (dentry == parent) { /* is root entry */ dput(parent); return false; } -- 2.7.4
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