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Fix crash when loading all follows

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This commit fixes a crash that caused the app to crash when getting all
the follows from a profile.

This issue was caused by a use-after-free memory error on inherited
transactions after the original transaction is deinitialized.

The issue was fixed by introducing a reference count on all transactions
and only deallocating the C transaction when the ref count goes to zero.

Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
This commit is contained in:
Daniel D’Aquino
2025-08-27 15:17:22 -07:00
parent a5aff15491
commit 9620dcf6ef
1 changed files with 36 additions and 14 deletions
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50
nostrdb/NdbTxn.swift
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@@ -39,6 +39,9 @@ class NdbTxn<T>: RawNdbTxnAccessible {
self.txn = active_txn self.txn = active_txn
self.inherited = true self.inherited = true
self.generation = Thread.current.threadDictionary["txn_generation"] as! Int self.generation = Thread.current.threadDictionary["txn_generation"] as! Int
let ref_count = Thread.current.threadDictionary["ndb_txn_ref_count"] as! Int
let new_ref_count = ref_count + 1
Thread.current.threadDictionary["ndb_txn_ref_count"] = new_ref_count
} else { } else {
self.txn = ndb_txn() self.txn = ndb_txn()
guard !ndb.is_closed else { return nil } guard !ndb.is_closed else { return nil }
@@ -52,6 +55,7 @@ class NdbTxn<T>: RawNdbTxnAccessible {
} }
self.generation = ndb.generation self.generation = ndb.generation
Thread.current.threadDictionary["ndb_txn"] = self.txn Thread.current.threadDictionary["ndb_txn"] = self.txn
Thread.current.threadDictionary["ndb_txn_ref_count"] = 1
Thread.current.threadDictionary["txn_generation"] = ndb.generation Thread.current.threadDictionary["txn_generation"] = ndb.generation
self.inherited = false self.inherited = false
} }
@@ -84,6 +88,20 @@ class NdbTxn<T>: RawNdbTxnAccessible {
print("txn: OLD GENERATION (\(self.generation) != \(ndb.generation)), IGNORING") print("txn: OLD GENERATION (\(self.generation) != \(ndb.generation)), IGNORING")
return return
} }
if ndb.is_closed {
print("txn: not closing. db closed")
return
}
if let ref_count = Thread.current.threadDictionary["ndb_txn_ref_count"] as? Int {
let new_ref_count = ref_count - 1
Thread.current.threadDictionary["ndb_txn_ref_count"] = new_ref_count
assert(new_ref_count >= 0, "NdbTxn reference count should never be below zero")
if new_ref_count <= 0 {
ndb_end_query(&self.txn)
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn")
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn_ref_count")
}
}
if inherited { if inherited {
print("txn: not closing. inherited ") print("txn: not closing. inherited ")
return return
@@ -92,18 +110,11 @@ class NdbTxn<T>: RawNdbTxnAccessible {
//print("txn: not closing. moved") //print("txn: not closing. moved")
return return
} }
if ndb.is_closed {
print("txn: not closing. db closed")
return
}
#if TXNDEBUG #if TXNDEBUG
txn_count -= 1; txn_count -= 1;
print("txn: close gen\(generation) '\(name)' \(txn_count)") print("txn: close gen\(generation) '\(name)' \(txn_count)")
#endif #endif
ndb_end_query(&self.txn)
//self.skip_close = true
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn")
} }
// functor // functor
@@ -159,6 +170,9 @@ class SafeNdbTxn<T: ~Copyable> {
txn = active_txn txn = active_txn
inherited = true inherited = true
generation = Thread.current.threadDictionary["txn_generation"] as! Int generation = Thread.current.threadDictionary["txn_generation"] as! Int
let ref_count = Thread.current.threadDictionary["ndb_txn_ref_count"] as! Int
let new_ref_count = ref_count + 1
Thread.current.threadDictionary["ndb_txn_ref_count"] = new_ref_count
} else { } else {
txn = ndb_txn() txn = ndb_txn()
guard !ndb.is_closed else { return nil } guard !ndb.is_closed else { return nil }
@@ -172,6 +186,7 @@ class SafeNdbTxn<T: ~Copyable> {
} }
generation = ndb.generation generation = ndb.generation
Thread.current.threadDictionary["ndb_txn"] = txn Thread.current.threadDictionary["ndb_txn"] = txn
Thread.current.threadDictionary["ndb_txn_ref_count"] = 1
Thread.current.threadDictionary["txn_generation"] = ndb.generation Thread.current.threadDictionary["txn_generation"] = ndb.generation
inherited = false inherited = false
} }
@@ -199,6 +214,20 @@ class SafeNdbTxn<T: ~Copyable> {
print("txn: OLD GENERATION (\(self.generation) != \(ndb.generation)), IGNORING") print("txn: OLD GENERATION (\(self.generation) != \(ndb.generation)), IGNORING")
return return
} }
if ndb.is_closed {
print("txn: not closing. db closed")
return
}
if let ref_count = Thread.current.threadDictionary["ndb_txn_ref_count"] as? Int {
let new_ref_count = ref_count - 1
Thread.current.threadDictionary["ndb_txn_ref_count"] = new_ref_count
assert(new_ref_count >= 0, "NdbTxn reference count should never be below zero")
if new_ref_count <= 0 {
ndb_end_query(&self.txn)
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn")
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn_ref_count")
}
}
if inherited { if inherited {
print("txn: not closing. inherited ") print("txn: not closing. inherited ")
return return
@@ -207,18 +236,11 @@ class SafeNdbTxn<T: ~Copyable> {
//print("txn: not closing. moved") //print("txn: not closing. moved")
return return
} }
if ndb.is_closed {
print("txn: not closing. db closed")
return
}
#if TXNDEBUG #if TXNDEBUG
txn_count -= 1; txn_count -= 1;
print("txn: close gen\(generation) '\(name)' \(txn_count)") print("txn: close gen\(generation) '\(name)' \(txn_count)")
#endif #endif
ndb_end_query(&self.txn)
//self.skip_close = true
Thread.current.threadDictionary.removeObject(forKey: "ndb_txn")
} }
// functor // functor