Commit ddbc22e2 authored Dec 10, 2014 by Rasmus Villemoes Committed by Linus Torvalds Dec 10, 2014

fs/hfs/catalog.c: fix comparison bug in hfs_cat_keycmp



Relying on the sign (after casting to int) of the difference of two
quantities for comparison is usually wrong.  For example, should a-b
turn out to be 2^31, the return value of cmp(a,b) is -2^31; but that
would also be the return value from cmp(b, a).  So a compares less than
b and b compares less than a.  One can also easily find three values
a,b,c such that a compares less than b, b compares less than c, but a
does not compare less than c.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 705304a8

fs/hfs/catalog.c

+8 −6

Original line number	Diff line number	Diff line
		@@ -162,14 +162,16 @@ err2:
		*/
		int hfs_cat_keycmp(const btree_key key1, const btree_key key2)
		{
		int retval;
		__be32 k1p, k2p;

		retval = be32_to_cpu(key1->cat.ParID) - be32_to_cpu(key2->cat.ParID);
		if (!retval)
		retval = hfs_strcmp(key1->cat.CName.name, key1->cat.CName.len,
		key2->cat.CName.name, key2->cat.CName.len);
		k1p = key1->cat.ParID;
		k2p = key2->cat.ParID;

		if (k1p != k2p)
		return be32_to_cpu(k1p) < be32_to_cpu(k2p) ? -1 : 1;

		return retval;
		return hfs_strcmp(key1->cat.CName.name, key1->cat.CName.len,
		key2->cat.CName.name, key2->cat.CName.len);
		}

		/* Try to get a catalog entry for given catalog id */

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