-From: Johannes Berg <johannes.berg@intel.com>
-Date: Tue, 9 Nov 2021 10:02:04 +0100
-Subject: [PATCH] mac80211: fix radiotap header generation
-
-In commit 8c89f7b3d3f2 ("mac80211: Use flex-array for radiotap header
-bitmap") we accidentally pointed the position to the wrong place, so
-we overwrite a present bitmap, and thus cause all kinds of trouble.
-
-To see the issue, note that the previous code read:
-
- pos = (void *)(it_present + 1);
-
-The requirement now is that we need to calculate pos via it_optional,
-to not trigger the compiler hardening checks, as:
-
- pos = (void *)&rthdr->it_optional[...];
-
-Rewriting the original expression, we get (obviously, since that just
-adds "+ x - x" terms):
-
- pos = (void *)(it_present + 1 + rthdr->it_optional - rthdr->it_optional)
-
-and moving the "+ rthdr->it_optional" outside to be used as an array:
-
- pos = (void *)&rthdr->it_optional[it_present + 1 - rthdr->it_optional];
-
-The original is off by one, fix it.
-
-Cc: stable@vger.kernel.org
-Fixes: 8c89f7b3d3f2 ("mac80211: Use flex-array for radiotap header bitmap")
-Reported-by: Sid Hayn <sidhayn@gmail.com>
-Signed-off-by: Johannes Berg <johannes.berg@intel.com>
-Tested-by: Sid Hayn <sidhayn@gmail.com>
-Reviewed-by: Kees Cook <keescook@chromium.org>
-Link: https://lore.kernel.org/r/20211109100203.c61007433ed6.I1dade57aba7de9c4f48d68249adbae62636fd98c@changeid
-Signed-off-by: Johannes Berg <johannes.berg@intel.com>
----
-
---- a/net/mac80211/rx.c
-+++ b/net/mac80211/rx.c
-@@ -364,7 +364,7 @@ ieee80211_add_rx_radiotap_header(struct
- * the compiler to think we have walked past the end of the
- * struct member.
- */
-- pos = (void *)&rthdr->it_optional[it_present - rthdr->it_optional];
-+ pos = (void *)&rthdr->it_optional[it_present + 1 - rthdr->it_optional];
-
- /* the order of the following fields is important */
-
projects / openwrt / openwrt.git / blobdiff