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| author | Dorian Rudolph <mail@dorianrudolph.com> | 2022-05-14 18:23:40 +0300 |
|---|---|---|
| committer | Sebastian Reichel <sre@kernel.org> | 2022-06-09 22:08:38 +0300 |
| commit | 093d27bb6f2d1963f927ef59c9a2d37059175426 (patch) | |
| tree | 7f1611046063d6f1d356acbd5200681e15851c1f /drivers/power | |
| parent | 80192eff64eee9b3bc0594a47381937b94b9d65a (diff) | |
| download | linux-093d27bb6f2d1963f927ef59c9a2d37059175426.tar.xz | |
power: supply: core: Fix boundary conditions in interpolation
The functions power_supply_temp2resist_simple and power_supply_ocv2cap_simple
handle boundary conditions incorrectly.
The change was introduced in a4585ba2050f460f749bbaf2b67bd56c41e30283
("power: supply: core: Use library interpolation").
There are two issues: First, the lines "high = i - 1" and "high = i" in ocv2cap
have the wrong order compared to temp2resist. As a consequence, ocv2cap
sets high=-1 if ocv>table[0].ocv, which causes an out-of-bounds read.
Second, the logic of temp2resist is also not correct.
Consider the case table[] = {{20, 100}, {10, 80}, {0, 60}}.
For temp=5, we expect a resistance of 70% by interpolation.
However, temp2resist sets high=low=2 and returns 60.
Cc: stable@vger.kernel.org
Signed-off-by: Dorian Rudolph <mail@dorianrudolph.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Fixes: a4585ba2050f ("power: supply: core: Use library interpolation")
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Diffstat (limited to 'drivers/power')
| -rw-r--r-- | drivers/power/supply/power_supply_core.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c index fad5890c899e..470253c337c7 100644 --- a/drivers/power/supply/power_supply_core.c +++ b/drivers/power/supply/power_supply_core.c @@ -846,17 +846,17 @@ int power_supply_temp2resist_simple(struct power_supply_resistance_temp_table *t { int i, high, low; - /* Break loop at table_len - 1 because that is the highest index */ - for (i = 0; i < table_len - 1; i++) + for (i = 0; i < table_len; i++) if (temp > table[i].temp) break; /* The library function will deal with high == low */ - if ((i == 0) || (i == (table_len - 1))) - high = i; + if (i == 0) + high = low = i; + else if (i == table_len) + high = low = i - 1; else - high = i - 1; - low = i; + high = (low = i) - 1; return fixp_linear_interpolate(table[low].temp, table[low].resistance, @@ -958,17 +958,17 @@ int power_supply_ocv2cap_simple(struct power_supply_battery_ocv_table *table, { int i, high, low; - /* Break loop at table_len - 1 because that is the highest index */ - for (i = 0; i < table_len - 1; i++) + for (i = 0; i < table_len; i++) if (ocv > table[i].ocv) break; /* The library function will deal with high == low */ - if ((i == 0) || (i == (table_len - 1))) - high = i - 1; + if (i == 0) + high = low = i; + else if (i == table_len) + high = low = i - 1; else - high = i; /* i.e. i == 0 */ - low = i; + high = (low = i) - 1; return fixp_linear_interpolate(table[low].ocv, table[low].capacity, |