macEnvExpand can segfault with very long variable values

[Andrew Johnson]

The macEnvExpand() code is apparently not robust against environment variables containing large strings. Krzysztof Lazarski at APS sector 19 triggers this occasionally.

[Andrew Johnson (anj)]

There doesn't seem to be a problem with handling large environment variables in iocsh on Linux. Need more information to track this any further.

[Andrew Johnson (anj)]

This issue may have been partly resolved by commit 12434 to the 3.14 tree. dbLoadTemplate() limited the number of macros that could be set by a substitution file, and had a fixed length string buffer to store them all in, with no overflow checks on either limit. The above commit allows the user to set dbTemplateMaxVars to increase the max number of variables (the buffer size is 50 times that) and checks for using too many variables, but it doesn't prevent a buffer overflow.

[Andrew Johnson (anj)]

No recent reports of problems, closing.