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authorNicolas Lacasse <nlacasse@google.com>2019-04-03 17:52:53 -0700
committerShentubot <shentubot@google.com>2019-04-03 17:53:56 -0700
commit61d8c361c6639ecbc262076be9f1214dd82065d1 (patch)
tree977c594b2ac67396fd7e4f9bf229c21a81f8b5b0 /pkg/sentry/fs/BUILD
parent4968dd1341a04e93557bdd9f4b4b83eb508e026d (diff)
Don't release d.mu in checks for child-existence.
Dirent.exists() is called in Create to check whether a child with the given name already exists. Dirent.exists() calls walk(), and before this CL allowed walk() to drop d.mu while calling d.Inode.Lookup. During this existence check, a racing Rename() can acquire d.mu and create a new child of the dirent with the same name. (Note that the source and destination of the rename must be in the same directory, otherwise renameMu will be taken preventing the race.) In this case, d.exists() can return false, even though a child with the same name actually does exist. This CL changes d.exists() so that it does not release d.mu while walking, thus preventing the race with Rename. It also adds comments noting that lockForRename may not take renameMu if the source and destination are in the same directory, as this is a bit surprising (at least it was to me). PiperOrigin-RevId: 241842579 Change-Id: I56524870e39dfcd18cab82054eb3088846c34813
Diffstat (limited to 'pkg/sentry/fs/BUILD')
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