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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2014-12-10 15:54:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:16 -0800
commitddbc22e27e672b6b180757ea1d7f8481dbb88128 (patch)
treedd1c05913129d4fc065054d275fb5b0112745649
parent705304a863cc41585508c0f476f6d3ec28cf7e00 (diff)
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>
-rw-r--r--fs/hfs/catalog.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/fs/hfs/catalog.c b/fs/hfs/catalog.c
index ff0316b925a5..db458ee3a546 100644
--- a/fs/hfs/catalog.c
+++ b/fs/hfs/catalog.c
@@ -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;
- return retval;
+ if (k1p != k2p)
+ return be32_to_cpu(k1p) < be32_to_cpu(k2p) ? -1 : 1;
+
+ 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 */