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| author | Johannes Berg <johannes.berg@intel.com> | 2021-11-09 10:02:04 +0100 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2021-11-15 10:55:20 +0100 |
| commit | c033a38a81bc539d6c0db8c5387e0b14d819a0cf (patch) | |
| tree | 7c7ec98b2093bfd48076c50feb64ebae59e8b81d /net/mac80211/rx.c | |
| parent | 77dfc2bc0bb4b8376ecd7a430f27a4a8fff6a5a0 (diff) | |
| download | linux-c033a38a81bc539d6c0db8c5387e0b14d819a0cf.tar.bz2 | |
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/rx.c')
| -rw-r--r-- | net/mac80211/rx.c | 2 |
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 */ |