integrity: Fix possible multiple allocation in integrity_inode_get()
When integrity_inode_get() is querying and inserting the cache, there
is a conditional race in the concurrent environment.
The race condition is the result of not properly implementing
"double-checked locking". In this case, it first checks to see if the
iint cache record exists before taking the lock, but doesn't check
again after taking the integrity_iint_lock.
Fixes: bf2276d10c
("ima: allocating iint improvements")
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
parent
db1d1e8b98
commit
9df6a4870d
@ -43,12 +43,10 @@ static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
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else if (inode > iint->inode)
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n = n->rb_right;
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else
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break;
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return iint;
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}
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if (!n)
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return NULL;
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return iint;
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return NULL;
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}
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/*
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@ -113,10 +111,15 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
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parent = *p;
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test_iint = rb_entry(parent, struct integrity_iint_cache,
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rb_node);
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if (inode < test_iint->inode)
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if (inode < test_iint->inode) {
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p = &(*p)->rb_left;
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else
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} else if (inode > test_iint->inode) {
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p = &(*p)->rb_right;
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} else {
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write_unlock(&integrity_iint_lock);
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kmem_cache_free(iint_cache, iint);
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return test_iint;
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}
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}
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iint->inode = inode;
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