dcache: don't expose uninitialized memory in /proc/<pid>/fd/<fd>
Well, it's not especially important that target->d_iname get the contents of dentry->d_iname, but it's important that it get initialized with *something*, otherwise we're just exposing some random piece of memory to anyone who reads the link at /proc/<pid>/fd/<fd> for the deleted file, when it's still held open by someone. I've run a test program that copies a short (<36 character) name ontop of a long (>=36 character) name and see that the first time I run it, without this patch, I get unpredicatable results out of /proc/<pid>/fd/<fd>. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -1479,6 +1479,8 @@ static void switch_names(struct dentry *dentry, struct dentry *target)
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* dentry:internal, target:external. Steal target's
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* storage and make target internal.
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*/
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memcpy(target->d_iname, dentry->d_name.name,
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dentry->d_name.len + 1);
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dentry->d_name.name = target->d_name.name;
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target->d_name.name = target->d_iname;
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}
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