[squid-dev] [PATCH] snprintf result used without validating its range

[Alex Rousskov]

On 02/09/2016 10:25 AM, Yuriy M. Kaminskiy wrote:
> Index: squid-3.5.13/src/log/File.cc
> ===================================================================
> --- squid-3.5.13.orig/src/log/File.cc
> +++ squid-3.5.13/src/log/File.cc
> @@ -104,13 +104,16 @@ logfilePrintf(Logfile * lf, const char *
...
> +    if (s < 0) {
> +        xstrncpy(buf, "snprintf error in logfilePrintf\n", sizeof(buf));
...


We should not write error messages to access.log. When an overflow
happens: If all logfilePrintf() callers cannot meaningfully handle the
error anyway, then we should just log the error message to cache.log and
return from logfilePrintf(). Otherwise, a more complex solution is needed.


N.B. IMHO, logging truncated lines is a bad idea but that wrong decision
was probably made long time ago, and changing it is both difficult and
probably outside your patch scope.


Thank you,

Alex.