6.15-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Berg johannes.berg@intel.com
[ Upstream commit 444020f4bf06fb86805ee7e7ceec0375485fd94d ]
This reverts commit e3eac9f32ec0 ("wifi: cfg80211: Annotate struct cfg80211_scan_request with __counted_by").
This really has been a completely failed experiment. There were no actual bugs found, and yet at this point we already have four "fixes" to it, with nothing to show for but code churn, and it never even made the code any safer.
In all of the cases that ended up getting "fixed", the structure is also internally inconsistent after the n_channels setting as the channel list isn't actually filled yet. You cannot scan with such a structure, that's just wrong. In mac80211, the struct is also reused multiple times, so initializing it once is no good.
Some previous "fixes" (e.g. one in brcm80211) are also just setting n_channels before accessing the array, under the assumption that the code is correct and the array can be accessed, further showing that the whole thing is just pointless when the allocation count and use count are not separate.
If we really wanted to fix it, we'd need to separately track the number of channels allocated and the number of channels currently used, but given that no bugs were found despite the numerous syzbot reports, that'd just be a waste of time.
Remove the __counted_by() annotation. We really should also remove a number of the n_channels settings that are setting up a structure that's inconsistent, but that can wait.
Reported-by: syzbot+e834e757bd9b3d3e1251@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e834e757bd9b3d3e1251 Fixes: e3eac9f32ec0 ("wifi: cfg80211: Annotate struct cfg80211_scan_request with __counted_by") Link: https://patch.msgid.link/20250714142130.9b0bbb7e1f07.I09112ccde72d445e11348f... Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/cfg80211.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h index efbd79c67be21..75f2e5782887f 100644 --- a/include/net/cfg80211.h +++ b/include/net/cfg80211.h @@ -2720,7 +2720,7 @@ struct cfg80211_scan_request { s8 tsf_report_link_id;
/* keep last */ - struct ieee80211_channel *channels[] __counted_by(n_channels); + struct ieee80211_channel *channels[]; };
static inline void get_random_mask_addr(u8 *buf, const u8 *addr, const u8 *mask)