Bug ID 511534: A large number of regular expressions in match rules on path-segments may cause an AAM policy to take too long to load,

Last Modified: Apr 10, 2019

Bug Tracker

Affected Product:  See more info
BIG-IP AAM(all modules)

Known Affected Versions:
11.2.1, 11.4.0, 11.4.1, 11.5.0, 11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4

Fixed In:
12.0.0, 11.6.0 HF5, 11.5.3 HF2, 11.4.1 HF9, 11.2.1 HF15

Opened: Mar 10, 2015
Severity: 3-Major
Related AskF5 Article:
K44288136

Symptoms

When loading an AAM policy, the tmm compiles the rules to an internal structure that is efficient for execution. Some conditions however may cause this process to take too long and the tmm gets halted before the system has finished compiling the policy.

Impact

The compilation time increases dramatically when regular expressions are used on more than one or two operands. Since conditions might exist on many different path-segments (e.g., the 1st, 2nd, 3rd, etc.), using regular expression on path-segments is a likely way to trigger this condition.

Conditions

The compilation time increases dramatically when regular expressions are used on more than one or 2 operands. Since you can have conditions on many different path-segments (e.g. the 1st, 2nd, 3rd, etc), using regular expression on path-segments are a likely way to trigger this condition.

Workaround

None.

Fix Information

Now, you can prevent AAM policy compilation from taking too long by turning the regular expression into plain matches using the '\' character to escape those symbols that turn a string into a regular expression. For example, previously, 'favicon.ico' was treated as a regular expression because '.' means 'any character'. Now the user can specify 'favicon\\.ico' (double '\' required by tmsh), which causes the '.' to mean the period character, thus avoiding the (unintended) regular expression.

Behavior Change