The function ieee80211_chsw_switch_vifs() calls the function
ieee80211_link_get_chanctx(), but does not check its return value.
The return value is a null pointer if the ieee80211_link_get_chanctx()
fails. This will lead to a null pointer dereference in the following
code "&old_ctx->conf". A proper implementation can be found in
ieee80211_link_use_reserved_assign().
Add a null pointer check and goto error handling path if the
function fails.
Fixes: 5d52ee811019 ("mac80211: allow reservation of a running chanctx")
Cc: stable@xxxxxxxxxxxxxxx # v3.16
Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
---
net/mac80211/chan.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index a442cb667520..9e6235001e0a 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -1503,6 +1503,10 @@ static int ieee80211_chsw_switch_vifs(struct ieee80211_local *local,
continue;
old_ctx = ieee80211_link_get_chanctx(link);
+ if (WARN_ON(old_ctx)) {
+ err = -EINVAL;
+ goto out;
+ }
vif_chsw[i].vif = &link->sdata->vif;
vif_chsw[i].old_ctx = &old_ctx->conf;
vif_chsw[i].new_ctx = &ctx->conf;
--
2.42.0.windows.2
