Messages in this thread Patch in this message | | | Date | Tue, 30 Jun 2009 17:23:51 -0700 | From | Greg KH <> | Subject | [patch 062/108] mac80211: fix minstrel single-rate memory corruption |
| |
2.6.30-stable review patch. If anyone has any objections, please let us know.
------------------
From: Bob Copeland <me@bobcopeland.com>
commit 5ee58d7e6ad019675b4090582aec4fa1180d8703 upstream.
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).
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- net/mac80211/rc80211_minstrel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -216,7 +216,7 @@ minstrel_get_next_sample(struct minstrel 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)
| |