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authorJohannes Berg <johannes.berg@intel.com>2011-11-04 11:01:46 +0100
committerJohn W. Linville <linville@tuxdriver.com>2011-11-07 13:19:14 -0500
commit3b6ef6334febb05d3050a96546e635f038dbcb15 (patch)
tree30f568f999c0ffd3a3011f0f495e759b7f19c2f7 /net
parent133a3ff2c934223a8143bfa52401bba962a97165 (diff)
cfg80211: fix cmp_ies
When comparing two items by IE, the sort order wasn't stable, which could lead to issues in the rbtree. Make it stable by making a missing IE sort before a present IE. Also sort by length first if it differs and then by contents. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net')
-rw-r--r--net/wireless/scan.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 0fb14241040..dc23b31594e 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -259,17 +259,20 @@ static int cmp_ies(u8 num, u8 *ies1, size_t len1, u8 *ies2, size_t len2)
{
const u8 *ie1 = cfg80211_find_ie(num, ies1, len1);
const u8 *ie2 = cfg80211_find_ie(num, ies2, len2);
- int r;
+ /* equal if both missing */
if (!ie1 && !ie2)
return 0;
- if (!ie1 || !ie2)
+ /* sort missing IE before (left of) present IE */
+ if (!ie1)
return -1;
+ if (!ie2)
+ return 1;
- r = memcmp(ie1 + 2, ie2 + 2, min(ie1[1], ie2[1]));
- if (r == 0 && ie1[1] != ie2[1])
+ /* sort by length first, then by contents */
+ if (ie1[1] != ie2[1])
return ie2[1] - ie1[1];
- return r;
+ return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
}
static bool is_bss(struct cfg80211_bss *a,