Re: [PATCH] mac80211: Add null pointer check for ieee80211_link_get_chanctx()

On Sun May 25, 2025 at 6:42 PM CEST, Wentao Liang wrote:

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@vger.kernel.org # v3.16 Signed-off-by: Wentao Liang vulab@iscas.ac.cn

---

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)) {
  

Don't you mean '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;