Solend v2.0.1 #131

0xripleys · 2023-02-24T21:03:23Z

This PR is 3 different features combined into one:

outflow limits
borrow coefficient
using two prices to limit borrows and withdraws

The first 3 commits link to descriptions of each feature.

tbh idk how PR diffs work but i wouldn't trust the individual feature PR diffs. I would only trust the commit diffs in this PR. In all likelihood, everything should be identical (i did check). But yeah I'm paranoid

codecov-commenter · 2023-02-24T21:31:58Z

Codecov Report

Merging #131 (477d85d) into upcoming (5a53f75) will increase coverage by 2.94%.
The diff coverage is 99.31%.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@             Coverage Diff              @@
##           upcoming     #131      +/-   ##
============================================
+ Coverage     79.96%   82.90%   +2.94%     
============================================
  Files            40       44       +4     
  Lines         12715    14814    +2099     
============================================
+ Hits          10167    12281    +2114     
+ Misses         2548     2533      -15

Impacted Files	Coverage Δ
token-lending/cli/src/main.rs	`0.06% <0.00%> (-0.01%)`	⬇️
...ng/program/tests/withdraw_obligation_collateral.rs	`100.00% <ø> (ø)`
token-lending/sdk/src/error.rs	`23.07% <ø> (ø)`
token-lending/sdk/src/state/mod.rs	`92.30% <ø> (ø)`
...lending/program/tests/deposit_reserve_liquidity.rs	`95.61% <93.75%> (-0.91%)`	⬇️
...lending/program/tests/redeem_reserve_collateral.rs	`96.33% <95.23%> (+0.72%)`	⬆️
token-lending/sdk/src/oracles.rs	`99.45% <97.05%> (+3.03%)`	⬆️
token-lending/program/src/processor.rs	`80.60% <97.14%> (+0.57%)`	⬆️
token-lending/sdk/src/state/rate_limiter.rs	`97.76% <97.76%> (ø)`
...nding/program/tests/borrow_obligation_liquidity.rs	`98.98% <99.43%> (+0.54%)`	⬆️
... and 20 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

Use a sliding window rate limiter to limit borrows and withdraws at the lending pool owner's discretion.

Add a borrow weight to the Reserve

- Add a smoothed_market_price to Reserve that is used to limit borrows and withdraws in cases where smoothed price and spot price diverge. - allowed_borrow_value now uses the min(smoothed_market_price, current spot price) - new field on obligation called borrowed_value_upper_bound that uses max(smoothed_market_price, current spot price)

chen-robert · 2023-03-13T14:22:32Z

token-lending/program/src/processor.rs

@@ -2024,6 +2071,11 @@ fn process_update_reserve_config(
        return Err(LendingError::InvalidMarketAuthority.into());
    }

+    // if window duration and max outflow are different, then create a new rate limiter instance.


nit: "and" should be "or"

chen-robert

Why are there rate limits on collateral redemptions (but not for liquidations?).

It seems like both cases should be similar -- my argument for collateral redemption safety is that the collateral must have been introduced into the system at some point by the same person. Absent some ctoken interest manipulation, it seems unlikely to incur that much additional risk. It's also not great UX if you deposit a lot and are unable to immediately withdraw I think.

On the other hand, maybe worth keeping as defense in depth.

chen-robert · 2023-03-13T14:22:56Z

token-lending/sdk/src/state/obligation.rs

    pub allowed_borrow_value: Decimal,
-    /// The dangerous borrow value at the weighted average liquidation threshold
+    /// The dangerous borrow value at the weighted average liquidation threshold.
+    /// ie sum(d.deposited_amount * d.liquidation_threshold * min(d.current_spot_price, d.smoothed_price)


This comment seems inaccurate, it doesn't consider the smoothed price for liquidation threshold right?

chen-robert · 2023-03-13T14:24:07Z

token-lending/sdk/src/oracles.rs

+    let market_price = pyth_price_to_decimal(&pyth_price);
+    let ema_price = {
+        let price_feed = price_account.to_price_feed(pyth_price_info.key);
+        // this can be unchecked bc the ema price is only used to _limit_ borrows and withdraws.


This seems true but also might be bad UX if you have a really outdated ema price that's never updated and users can never initiate a borrow/withdraw.

That being said, from my light skimming of pyth code it seems like EMA should always be updated the same slot as the latest valid price update, so not sure if it practically matters

That being said, from my light skimming of pyth code it seems like EMA should always be updated the same slot as the latest valid price update, so not sure if it practically matters

err yeah this was also partially my reasoning, ill update the comment

chen-robert · 2023-03-13T14:24:21Z

token-lending/sdk/src/state/lending_market.rs

@@ -62,6 +65,8 @@ pub struct InitLendingMarketParams {
    pub oracle_program_id: Pubkey,
    /// Oracle (Switchboard) program id
    pub switchboard_oracle_program_id: Pubkey,
+    /// Current slot
+    pub current_slot: u64,


Why was this added?

ah, i used to call RateLimiter::new() in init_lending_market, which needed the current slot. but then later i added a Default implementation. will remove

chen-robert · 2023-03-13T14:25:26Z

token-lending/program/src/processor.rs

-            }
-            withdraw_amount
-        };
-        if withdraw_amount == 0 {


Why was this removed? I don't think it has an impact but just curious

all this logic got moved into max_withdraw_amount in reserve.rs for easier testing, and also i think it was hard to modify this logic as is after adding the two prices stuff

max_withdraw_amount and withdraw_amount are separate and I don't think this check gets added to the other call right

oh sorry were you asking specifically about if withdraw_amount == 0? Yeah I guess it doesn't matter, although I think i just I just forgot to re-add it

edit: i did add this check further below

if max_withdraw_amount == 0 { msg!("Maximum withdraw value is zero"); return Err(LendingError::WithdrawTooLarge.into()); }

which yeah i guess isn't the same thing. i could change it back i guess, don't think it matters

yeah don't feel too strongly (but why risk it)

will change tmrw

chen-robert · 2023-03-13T14:25:57Z

token-lending/sdk/src/math/decimal.rs

@@ -55,6 +55,11 @@ impl Decimal {
        Self(U192::from(percent as u64 * PERCENT_SCALER))
    }

+    /// Create scaled decimal from bps value
+    pub fn from_bps(bps: u64) -> Self {


This (and the other from_percent) breaks at around 1800% since you multiply before calling ::from. Just a heads up

ah good catch. yeah i think we want to set the borrow weight as high as possible. will fix

chen-robert · 2023-03-13T14:26:51Z

token-lending/program/src/processor.rs

+            .rate_limiter
+            .update(
+                clock.slot,
+                reserve.market_value(Decimal::from(liquidity_amount))?,


It seems like this should be based on worst-case market value right?

heh, yeah. i did this PR before adding the 2 prices stuff. will change

nope-finance · 2023-03-13T20:40:11Z

Why are there rate limits on collateral redemptions (but not for liquidations?).

usually exploits occur able to overborrow or overwithdraw (or both) so having the limit on both makes sense.

for liquidations, without the ability to reliably internalize liquidations it's not great to implicitly block liquidations from happening when needed with a rate limiter as liquidators will just run out of money pretty quickly on a large price movement.

0xripleys changed the title ~~0xripleys outflow limits (#125)~~ Solend v2.1 Feb 24, 2023

nope-finance changed the title ~~Solend v2.1~~ Solend v2.0.1 Feb 25, 2023

0xripleys marked this pull request as ready for review February 28, 2023 20:00

0xripleys added 3 commits March 7, 2023 18:03

0xripleys outflow limits (#125)

95a4e55

Use a sliding window rate limiter to limit borrows and withdraws at the lending pool owner's discretion.

0xripleys borrow coefficient (#127)

be92df7

Add a borrow weight to the Reserve

0xripleys force-pushed the v2_upcoming branch from 9e4711e to e2e44ad Compare March 7, 2023 23:05

chen-robert reviewed Mar 13, 2023

View reviewed changes

0xripleys and others added 4 commits March 13, 2023 19:52

audit nits

477d85d

audit fixes pt 2

817909b

disable rate limiter if window duration == 0

731d758

cli changes for v2.0.1 (#133)

9340ac6

nope-finance merged commit 5122002 into upcoming Mar 28, 2023

nope-finance deleted the v2_upcoming branch March 28, 2023 02:50

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Solend v2.0.1 #131

Solend v2.0.1 #131

0xripleys commented Feb 24, 2023 •

edited

Loading

codecov-commenter commented Feb 24, 2023 •

edited

Loading

chen-robert Mar 13, 2023

chen-robert left a comment

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

chen-robert Mar 15, 2023

0xripleys Mar 15, 2023 •

edited

Loading

chen-robert Mar 15, 2023

0xripleys Mar 15, 2023

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

chen-robert Mar 13, 2023

0xripleys Mar 13, 2023

nope-finance commented Mar 13, 2023

Solend v2.0.1 #131

Solend v2.0.1 #131

Conversation

0xripleys commented Feb 24, 2023 • edited Loading

codecov-commenter commented Feb 24, 2023 • edited Loading

Codecov Report

Choose a reason for hiding this comment

chen-robert left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

0xripleys Mar 15, 2023 • edited Loading

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

nope-finance commented Mar 13, 2023

0xripleys commented Feb 24, 2023 •

edited

Loading

codecov-commenter commented Feb 24, 2023 •

edited

Loading

0xripleys Mar 15, 2023 •

edited

Loading