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cfg80211: fix cmp_ies

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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>
This commit is contained in:
Johannes Berg 2011-11-04 11:01:46 +01:00 committed by John W. Linville
parent 133a3ff2c9
commit 3b6ef6334f
1 changed files with 8 additions and 5 deletions
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13
net/wireless/scan.c
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@ -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,