From 588ef9d411339012fc3c94bfad8911e9d0a517a2 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 23 Mar 2015 15:29:23 +0000 Subject: [PATCH] bt-sdp: fix broken uuids power-of-2 calculation The binary search in sdp_uuid_match() only works when the number of elements to search is a power of two. lo = record->uuid; hi = record->uuids; while (hi >>= 1) if (lo[hi] <= val) lo += hi; return *lo == val; I noticed that the record->uuids calculation in sdp_service_record_build() was suspect: record->uuids = 1 << ffs(record->uuids - 1); Unlike most ffs(val) - 1 users, the expression is ffs(val - 1)! Actually ffs() is the wrong function to use for power-of-2. Use pow2ceil() to achieve the correct effect. Now the record->uuid[] array is sized correctly and the binary search in sdp_uuid_match() should work. I'm not sure how to run/test this code. Cc: Andrzej Zaborowski Cc: qemu-stable@nongnu.org Signed-off-by: Stefan Hajnoczi Message-id: 1427124571-28598-2-git-send-email-stefanha@redhat.com Signed-off-by: Kevin Wolf --- hw/bt/sdp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/bt/sdp.c b/hw/bt/sdp.c index 218e075df7..c903747952 100644 --- a/hw/bt/sdp.c +++ b/hw/bt/sdp.c @@ -707,7 +707,7 @@ static void sdp_service_record_build(struct sdp_service_record_s *record, len += sdp_attr_max_size(&def->attributes[record->attributes ++].data, &record->uuids); } - record->uuids = 1 << ffs(record->uuids - 1); + record->uuids = pow2ceil(record->uuids); record->attribute_list = g_malloc0(record->attributes * sizeof(*record->attribute_list)); record->uuid =