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authorJohannes Berg <johannes.berg@intel.com>2021-11-09 10:02:04 +0100
committerJohannes Berg <johannes.berg@intel.com>2021-11-15 10:55:20 +0100
commitc033a38a81bc539d6c0db8c5387e0b14d819a0cf (patch)
tree7c7ec98b2093bfd48076c50feb64ebae59e8b81d /net/mac80211
parent77dfc2bc0bb4b8376ecd7a430f27a4a8fff6a5a0 (diff)
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>
Diffstat (limited to 'net/mac80211')
-rw-r--r--net/mac80211/rx.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 6360c664259f..1b0bd642dc23 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -364,7 +364,7 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
* 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 */