diff options
| author | Bob Copeland <me@bobcopeland.com> | 2009-06-05 08:21:50 -0400 |
|---|---|---|
| committer | John W. Linville <linville@tuxdriver.com> | 2009-06-10 13:27:51 -0400 |
| commit | 5ee58d7e6ad019675b4090582aec4fa1180d8703 (patch) | |
| tree | 1f6cb14a99e1b629bf9dcba2879feaf62a463af5 | |
| parent | 4d1d49858c0a5a4fb1be4bc7972754cd640245ba (diff) | |
mac80211: fix minstrel single-rate memory corruption
The minstrel rate controller periodically looks up rate indexes in
a sampling table. When accessing a specific row and column, minstrel
correctly does a bounds check which, on the surface, appears to handle
the case where mi->n_rates < 2. However, mi->sample_idx is actually
defined as an unsigned, so the right hand side is taken to be a huge
positive number when negative, and the check will always fail.
Consequently, the RC will overrun the array and cause random memory
corruption when communicating with a peer that has only a single rate.
The max value of mi->sample_idx is around 25 so casting to int should
have no ill effects.
Without the change, uptime is a few minutes under load with an AP
that has a single hard-coded rate, and both the AP and STA could
potentially crash. With the change, both lasted 12 hours with a
steady load.
Thanks to Ognjen Maric for providing the single-rate clue so I could
reproduce this.
This fixes http://bugzilla.kernel.org/show_bug.cgi?id=12490 on the
regression list (also http://bugzilla.kernel.org/show_bug.cgi?id=13000).
Cc: stable@kernel.org
Reported-by: Sergey S. Kostyliov <rathamahata@gmail.com>
Reported-by: Ognjen Maric <ognjen.maric@gmail.com>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
| -rw-r--r-- | net/mac80211/rc80211_minstrel.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c index 0a11515341ba..b218b98fba7f 100644 --- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -215,7 +215,7 @@ minstrel_get_next_sample(struct minstrel_sta_info *mi) unsigned int sample_ndx; sample_ndx = SAMPLE_TBL(mi, mi->sample_idx, mi->sample_column); mi->sample_idx++; - if (mi->sample_idx > (mi->n_rates - 2)) { + if ((int) mi->sample_idx > (mi->n_rates - 2)) { mi->sample_idx = 0; mi->sample_column++; if (mi->sample_column >= SAMPLE_COLUMNS) |