710970 - Possible bad null-check in mjit::Compiler::performCompilation()

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Justin Dolske [:Dolske]]

From http://www.viva64.com/en/a/0078/

Example 4. Checking a pointer for NULL only after it had been used

CompileStatus
mjit::Compiler::performCompilation(JITScript **jitp)
{
  ...
  JaegerSpew(JSpew_Scripts,
    "successfully compiled (code \"%p\") (size \"%u\")\n",
    (*jitp)->code.m_code.executableAddress(),
    unsigned((*jitp)->code.m_size));

  if (!*jitp)
      return Compile_Abort;
  ...
}

PVS-Studio diagnostic message: V595 The '* jitp' pointer was utilized before it was verified against nullptr. Check lines: 547, 549. compiler.cpp 547

By the way, using a pointer before checking it is a wide-spread error. This was one more example of this kind.

Comment 1

[David Mandelin [:dmandelin]]

Attachment: Patch

False positive/nit: finishThisUp returns Okay only iff *jitp is non-null.

Comment 2

[David Anderson [:dvander] - inactive, e-mail if emergency]

Comment on attachment 582111 [details] [diff] [review]
Patch

Gah hit wrong button.

Comment 3

[David Mandelin [:dmandelin]]

http://hg.mozilla.org/integration/mozilla-inbound/rev/092b0f19e65a

Comment 4

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/092b0f19e65a