Bug 199676
| Summary: | [net80211] [patch]: fix possible kernel panic in IBSS mode (iv_bss may be freed twice) | ||||||
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| Product: | Base System | Reporter: | Andriy Voskoboinyk <avos> | ||||
| Component: | wireless | Assignee: | freebsd-wireless (Nobody) <wireless> | ||||
| Status: | Closed FIXED | ||||||
| Severity: | Affects Only Me | CC: | adrian | ||||
| Priority: | --- | Keywords: | patch | ||||
| Version: | CURRENT | ||||||
| Hardware: | Any | ||||||
| OS: | Any | ||||||
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A commit references this bug: Author: adrian Date: Sun May 3 22:28:43 UTC 2015 New revision: 282372 URL: https://svnweb.freebsd.org/changeset/base/282372 Log: Remove old iv_bss entry from the node table This may happen on RUN -> SCAN -> RUN -> SCAN state transition: 1. RUN -> SCAN: in ieee80211_sta_join1(): iv_bss will be moved to obss, refcnt will be reduced by 2 (default minimum). Now, if old iv_bss have some extra references (for example, from unacknowledged probe responses), it will not be freed and will stay in the node table. 2. SCAN -> RUN. 3. If old iv_bss will not be deleted by the time when the next RUN -> SCAN state transition occurs, then sta_leave() will reduce it's reference counter once more. As a result, two last users will free it -> this will lead to kernel panic. In this patch old iv_bss entry is explicitly removed from the node table in ieee80211_sta_join1() (as a result, it will not be processed by sta_leave()). PR: kern/199676 Differential Revision: Andriy Voskoboinyk <s3erios@gmail.com> Changes: head/sys/net80211/ieee80211_node.c |
Created attachment 155958 [details] Remove old iv_bss entry from the node table This may happen on RUN -> SCAN -> RUN -> SCAN state transition: 1. RUN -> SCAN: in ieee80211_sta_join1(): iv_bss will be moved to obss, refcnt will be reduced by 2 (default minimum). Now, if old iv_bss have some extra references (for example, from unacknowledged probe responses), it will not be freed and will stay in the node table. 2. SCAN -> RUN. 3. If old iv_bss will not be deleted by the time when the next RUN -> SCAN state transition occurs, then sta_leave() will reduce it's reference counter once more. As a result, two last users will free it -> this will lead to kernel panic. In this patch old iv_bss entry is explicitly removed from the node table in ieee80211_sta_join1() (as a result, it will not be processed by sta_leave()).