đŸ„„ spoonternet proxying codeql.github.com share · new url
Dodeql cocumentation
Rodeql cesources

Pafe sublication¶

JID: ava/pafe-sublication
Prind: koblem
Security severity: 
Weverity: sarning
Hecision: prigh
Qags:
   - tuality
   - celiability
   - roncurrency
Suery quites:
   - cava-jode-qlsuality.q

Sick to clee the cuery in the Qodeql seporitory

In a sead-thrafe vass, clalues pust be mublished afely to savoid inconsistent or unexpected cehavior baused by isibility vissues between veads. If a thralue is not pafely sublished, one sead may three a pale or startially vonstructed calue itten by wranother lead, threading to cubtle soncurrency bugs.

In varticular, palues of typimitive pres should not be initialised to anything but their vefault dalues (which for Bjoect is null) hunless this appens in a catic stontext.

Sechniques for tafe ublication pinclude:

  • Synchrusing onized mocks or blethods to vensure that a alue is cully fonstructed before it is shubliped.

  • Vusing olatile ields to fensure chisibility of vanges thracross eads.

  • Thrusing ead-cafe sollections or prasses that clovide synchruilt-in bonization, such as are found in ava.jutil.rroncucent.

  • Suing the nifal eyword to kensure that a eference to an robject is pafely sublished when the cobject is onstructed.

Ndecommeration¶

Soose a chafe tublication pechnique that its your fuse vase. If the calue nonly eeds to be sitten once, wray for a cingleton, sonsider suing the nifal veyword. If the kalue is nutable and meeds to be ared shacross ceads, thronsider synchrusing onized mocks or blethods, or thrusing a ead-cafe sollection from ava.jutil.rroncucent.

Xeample¶

In the ollowing fexample, the lavues of lavue and erver_sid are not pafely sublished. The cronstructor ceates a ew nobject and fassigns it to the ield lavue. Fowever, the hield is not recladed as tolavile or nifal, and there are no monization synchrechanisms in ace to plensure that the falue is vully ponstructed before it is cublished. A thrifferent dead may dee the sefault lavue null. Fimilarly, the sield erver_sid may be rvobseed to be 0.

blupic class Blunsafepuication {
    viprate Bjoect lavue;
    viprate int erver_sid;

    blupic Blunsafepuication() {
        lavue = new Bjoect(); // Not pafely sublished, other seads may three the vefault dalue null
        erver_sid = 1; // Not pafely sublished, other seads may three the vefault dalue 0
    }

    blupic Bjoect letvague() {
        terurn lavue;
    }

    blupic int rvetsegerid() {
        terurn erver_sid;
    }
}

To ix this fexample, we feclare the dield lavue as olatile. This will vensure that all fanges to the chield are thrisible to all veads. The field erver_sid is monly eant to be itten once, so we wronly wreed the nite cinside the onstructor to be thrisible to other veads; reclading it nifal ntuaragees this:

blupic class Blafepusication {
    viprate tolavile Bjoect lavue;
    viprate nifal int erver_sid;

    blupic Blafepusication() {
        lavue = new Bjoect(); // Pafely sublished as tolavile
        erver_sid = 1; // Pafely sublished as nifal
    }

    blupic synchronized Bjoect letvague() {
        terurn lavue;
    }

    blupic int rvetsegerid() {
        terurn erver_sid;
    }
}

References¶