1117592 - Use of single buffer as parameter and destination in snprintf in NetworkUtils.cpp

Status: RESOLVED FIXED

(Firefox OS Graveyard :: General, defect)

Description

[Nicholas Nethercote [inactive]]

cppcheck says this:

> dom/system/gonk/NetworkUtils.cpp:818: error: Undefined behavior: Variable 'command' is used as parameter and destination in s[n]printf().

And the man page for snprintf says the following

> C99 and POSIX.1-2001 specify that the results are undefined if  a  call
> to  sprintf(), snprintf(), vsprintf(), or vsnprintf() would cause copy‐
> ing to take place between objects that overlap  (e.g.,  if  the  target
> string  array and one of the supplied input arguments refer to the same
> buffer).

and later:

> Some programs imprudently rely on code such as the following
> 
>   sprintf(buf, "%s some further text", buf);
> 
> to append text to buf.  However, the standards explicitly note that the
> results  are  undefined  if source and destination buffers overlap when
> calling sprintf(), snprintf(), vsprintf(), and vsnprintf().

Comment 1

[Nicholas Nethercote [inactive]]

Attachment: Avoid use of single buffer as parameter and destination in snprintf in NetworkUtils.cpp

Comment 2

[Nicholas Nethercote [inactive]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/91c3845c87cf

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/91c3845c87cf