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vm: fix deadlock in UnusedTCPPort #5658

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a-nogikh merged 1 commit into from
Jan 13, 2025
+15 −0
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vm: fix deadlock in UnusedTCPPort #5658

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15 changes: 15 additions & 0 deletions vm/vmimpl/vmimpl.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,10 @@ import (
"io"
"math/big"
"net"
"os"
"os/exec"
"strings"
"syscall"
"time"

"github.com/google/syzkaller/pkg/log"
Expand Down Expand Up @@ -241,6 +243,19 @@ func UnusedTCPPort() int {
ln.Close()
return port
}

// Continue searching for a port only if we fail with EADDRINUSE or don't have permissions to use this port.
// Although we exclude ports <1024 in RandomPort(), it's still possible that we can face a restricted port.
var opErr *net.OpError
if errors.As(err, &opErr) && opErr.Op == "listen" {
var syscallErr *os.SyscallError
if errors.As(opErr.Err, &syscallErr) {
if errors.Is(syscallErr.Err, syscall.EADDRINUSE) || errors.Is(syscallErr.Err, syscall.EACCES) {
continue
}
}
}
log.Fatalf("error allocating port localhost:%d: %v", port, err)
}
}

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