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iwlwifi: mvm: fix possible out-of-bounds read when accessing lq_info 

lq_info is an arary of size 2, active_tbl index is u8.
When accessing lq_info[1 - active_tbl], theoretically it's possible
that the access will be made to a negative index value.

Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Gregory Greenman 2019-07-08 09:07:42 +03:00 committed by Johannes Berg
parent ecd09ddc1d
commit 514ea05b07
1 changed files with 20 additions and 8 deletions
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28
drivers/net/wireless/intel/iwlwifi/mvm/rs.c
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@ -1352,6 +1352,18 @@ static void rs_set_expected_tpt_table(struct iwl_lq_sta *lq_sta,
tbl->expected_tpt = rs_get_expected_tpt_table(lq_sta, column, rate->bw);
}
/* rs uses two tables, one is active and the second is for searching better
* configuration. This function, according to the index of the currently
* active table returns the search table, which is located at the
* index complementary to 1 according to the active table (active = 1,
* search = 0 or active = 0, search = 1).
* Since lq_info is an arary of size 2, make sure index cannot be out of bounds.
*/
static inline u8 rs_search_tbl(u8 active_tbl)
{
return (active_tbl ^ 1) & 1;
}
static s32 rs_get_best_rate(struct iwl_mvm *mvm,
struct iwl_lq_sta *lq_sta,
struct iwl_scale_tbl_info *tbl, /* "search" */
@ -1699,9 +1711,9 @@ static int rs_switch_to_column(struct iwl_mvm *mvm,
struct ieee80211_sta *sta,
enum rs_column col_id)
{
struct iwl_scale_tbl_info *tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
struct iwl_scale_tbl_info *tbl = &lq_sta->lq_info[lq_sta->active_tbl];
struct iwl_scale_tbl_info *search_tbl =
&(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
&lq_sta->lq_info[rs_search_tbl(lq_sta->active_tbl)];
struct rs_rate *rate = &search_tbl->rate;
const struct rs_tx_column *column = &rs_tx_columns[col_id];
const struct rs_tx_column *curr_column = &rs_tx_columns[tbl->column];
@ -2109,7 +2121,7 @@ static void rs_rate_scale_perform(struct iwl_mvm *mvm,
if (!lq_sta->search_better_tbl)
active_tbl = lq_sta->active_tbl;
else
active_tbl = 1 - lq_sta->active_tbl;
active_tbl = rs_search_tbl(lq_sta->active_tbl);
tbl = &(lq_sta->lq_info[active_tbl]);
rate = &tbl->rate;
@ -2333,7 +2345,7 @@ static void rs_rate_scale_perform(struct iwl_mvm *mvm,
/* If new "search" mode was selected, set up in uCode table */
if (lq_sta->search_better_tbl) {
/* Access the "search" table, clear its history. */
tbl = &(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
tbl = &lq_sta->lq_info[rs_search_tbl(lq_sta->active_tbl)];
rs_rate_scale_clear_tbl_windows(mvm, tbl);
/* Use new "search" start rate */
@ -2676,7 +2688,7 @@ static void rs_initialize_lq(struct iwl_mvm *mvm,
if (!lq_sta->search_better_tbl)
active_tbl = lq_sta->active_tbl;
else
active_tbl = 1 - lq_sta->active_tbl;
active_tbl = rs_search_tbl(lq_sta->active_tbl);
tbl = &(lq_sta->lq_info[active_tbl]);
rate = &tbl->rate;
@ -3172,9 +3184,9 @@ static void __iwl_mvm_rs_tx_status(struct iwl_mvm *mvm,
if (!lq_sta->search_better_tbl) {
curr_tbl = &lq_sta->lq_info[lq_sta->active_tbl];
other_tbl = &lq_sta->lq_info[1 - lq_sta->active_tbl];
other_tbl = &lq_sta->lq_info[rs_search_tbl(lq_sta->active_tbl)];
} else {
curr_tbl = &lq_sta->lq_info[1 - lq_sta->active_tbl];
curr_tbl = &lq_sta->lq_info[rs_search_tbl(lq_sta->active_tbl)];
other_tbl = &lq_sta->lq_info[lq_sta->active_tbl];
}
@ -3183,7 +3195,7 @@ static void __iwl_mvm_rs_tx_status(struct iwl_mvm *mvm,
"Neither active nor search matches tx rate\n");
tmp_tbl = &lq_sta->lq_info[lq_sta->active_tbl];
rs_dump_rate(mvm, &tmp_tbl->rate, "ACTIVE");
tmp_tbl = &lq_sta->lq_info[1 - lq_sta->active_tbl];
tmp_tbl = &lq_sta->lq_info[rs_search_tbl(lq_sta->active_tbl)];
rs_dump_rate(mvm, &tmp_tbl->rate, "SEARCH");
rs_dump_rate(mvm, &lq_rate, "ACTUAL");