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Release the lock after reading all the fields from FileAsync in NotifyEvent.

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This CL makes changes to read all the fields from FAsync struct at once to
avoid inconsistent results when FileAsync is changed.

PiperOrigin-RevId: 543528321
This commit is contained in:
Nayana Bidari
2023-06-26 13:41:57 -07:00
committed by gVisor bot
parent 22fc34339b
commit 76a0532368
1 changed files with 20 additions and 17 deletions
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pkg/sentry/kernel/fasync/fasync.go
+20 -17
View File
@@ -88,20 +88,21 @@ type FileAsync struct {
// NotifyEvent implements waiter.EventListener.NotifyEvent.
func (a *FileAsync) NotifyEvent(mask waiter.EventMask) {
a.mu.Lock()
locked := true
defer func() {
if locked {
a.mu.Unlock()
}
}()
if !a.registered {
a.mu.Unlock()
return
}
// Read all the required fields which are lock protected from FileAsync
// and release the lock.
t := a.recipientT
tg := a.recipientTG
creds := a.requester
sig := a.signal
if a.recipientPG != nil {
tg = a.recipientPG.Originator()
}
a.mu.Unlock()
if tg != nil {
t = tg.Leader()
}
@@ -109,13 +110,13 @@ func (a *FileAsync) NotifyEvent(mask waiter.EventMask) {
// No recipient has been registered.
return
}
c := t.Credentials()
tCreds := t.Credentials()
// Logic from sigio_perm in fs/fcntl.c.
permCheck := (a.requester.EffectiveKUID == 0 ||
a.requester.EffectiveKUID == c.SavedKUID ||
a.requester.EffectiveKUID == c.RealKUID ||
a.requester.RealKUID == c.SavedKUID ||
a.requester.RealKUID == c.RealKUID)
permCheck := (creds.EffectiveKUID == 0 ||
creds.EffectiveKUID == tCreds.SavedKUID ||
creds.EffectiveKUID == tCreds.RealKUID ||
creds.RealKUID == tCreds.SavedKUID ||
creds.RealKUID == tCreds.RealKUID)
if !permCheck {
return
}
@@ -123,8 +124,8 @@ func (a *FileAsync) NotifyEvent(mask waiter.EventMask) {
Signo: int32(linux.SIGIO),
Code: linux.SI_KERNEL,
}
if a.signal != 0 {
signalInfo.Signo = int32(a.signal)
if sig != 0 {
signalInfo.Signo = int32(sig)
signalInfo.SetFD(uint32(a.fd))
var band int64
for m, bandCode := range bandTable {
@@ -134,9 +135,11 @@ func (a *FileAsync) NotifyEvent(mask waiter.EventMask) {
}
signalInfo.SetBand(band)
}
a.mu.Unlock()
locked = false
t.SendSignal(signalInfo)
if tg != nil {
t.SendGroupSignal(signalInfo)
} else {
t.SendSignal(signalInfo)
}
}
// Register sets the file which will be monitored for IO events.