[GH-ISSUE #1528] A bug in the init() method of the WiFiManagerParameter class #1304

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opened 2026-02-28 01:29:29 +03:00 by kerem · 3 comments

kerem commented

2026-02-28 01:29:29 +03:00

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Originally created by @Mollayo on GitHub (Dec 1, 2022).
Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/1528

I believe I found a bug in the init() method of the WiFiManagerParameter class.

In this init() method, the value of _length is set to 1 by default. See here:
github.com/tzapu/WiFiManager@9f5981e2fd/WiFiManager.cpp (L61)
The _value variable is also initialised to nullptr.

This init() method is then using the setValue() method to allocate the pointer for _value. However, the allocation is not made in case the length parameter in the init() function is set to 1 because of the condition "if(_length != length)" not being satisfied. See here:
github.com/tzapu/WiFiManager@9f5981e2fd/WiFiManager.cpp (L91)

In consequence, the _value variable is still equal to nullptr after calling the init() method, making WifiManager to crash.

One solution would be to write " _value = new char[_length + 1]; " instead of "_value = nullptr;" at this line:
github.com/tzapu/WiFiManager@fe9774fe0f/WiFiManager.cpp (L62)

Originally created by @Mollayo on GitHub (Dec 1, 2022). Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/1528 I believe I found a bug in the init() method of the WiFiManagerParameter class. In this init() method, the value of _length is set to 1 by default. See here: https://github.com/tzapu/WiFiManager/blob/9f5981e2fd40db86780299d5ba3a3840b891a998/WiFiManager.cpp#L61 The _value variable is also initialised to nullptr. This init() method is then using the setValue() method to allocate the pointer for _value. However, the allocation is not made in case the length parameter in the init() function is set to 1 because of the condition "if(_length != length)" not being satisfied. See here: https://github.com/tzapu/WiFiManager/blob/9f5981e2fd40db86780299d5ba3a3840b891a998/WiFiManager.cpp#L91 In consequence, the _value variable is still equal to nullptr after calling the init() method, making WifiManager to crash. One solution would be to write " _value = new char[_length + 1]; " instead of "_value = nullptr;" at this line: https://github.com/tzapu/WiFiManager/blob/fe9774fe0f231767f3fc59de1a03a9c44f06adc3/WiFiManager.cpp#L62

kerem

2026-02-28 01:29:29 +03:00

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kerem commented

2026-02-28 01:29:30 +03:00

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@tablatronix commented on GitHub (Dec 1, 2022):

Yeah there are 2 issues on this, I have not had a chance to look at it

#1504
#1521

@tablatronix commented on GitHub (Dec 1, 2022): Yeah there are 2 issues on this, I have not had a chance to look at it #1504 #1521

kerem commented

2026-02-28 01:29:30 +03:00

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@tablatronix commented on GitHub (Dec 1, 2022):

or
if(_length != length || _value == nullptr){ perhaps?

@tablatronix commented on GitHub (Dec 1, 2022): or ` if(_length != length || _value == nullptr){` perhaps?

kerem commented

2026-02-28 01:29:30 +03:00

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@tablatronix commented on GitHub (Dec 1, 2022):

I forget why I used length =1
I think 0 made it not possible to detect un-initialized params or out of scope objs.

at some point this will have to be rewritten with smart pointers or safer memory handling

@tablatronix commented on GitHub (Dec 1, 2022): I forget why I used length =1 I think 0 made it not possible to detect un-initialized params or out of scope objs. at some point this will have to be rewritten with smart pointers or safer memory handling