From 321bcf92163038e2b96fd3bf9bc29f755c81d9ef Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Sun, 21 Oct 2007 16:41:38 -0700 Subject: [PATCH] dcache: don't expose uninitialized memory in /proc//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//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//fd/. Signed-off-by: J. Bruce Fields Cc: Al Viro Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/dcache.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index 2bb3f7ac683b..d9ca1e5ceb92 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1479,6 +1479,8 @@ static void switch_names(struct dentry *dentry, struct dentry *target) * dentry:internal, target:external. Steal target's * storage and make target internal. */ + memcpy(target->d_iname, dentry->d_name.name, + dentry->d_name.len + 1); dentry->d_name.name = target->d_name.name; target->d_name.name = target->d_iname; } -- 2.20.1