Reputation: 1089

Compilation error: stray ‘\302’ in program, etc

I have a problem compiling the following exploit code:

http://downloads.securityfocus.com/vulnerabilities/exploits/59846-1.c

I am using "gcc file.c" and "gcc -O2 file.c", but both of them results in the following errors:

sorbolinux-exec.c: In function ‘sc’:
sorbolinux-exec.c:76: error: stray ‘\302’ in program
sorbolinux-exec.c:76: error: stray ‘\244’ in program
sorbolinux-exec.c:76: error: ‘t’ undeclared (first use in this function)
sorbolinux-exec.c:76: error: (Each undeclared identifier is reported only  once
sorbolinux-exec.c:76: error: for each function it appears in.)

I tried compiling them on both Kali Linux and Ubuntu 10.04 (Lucid Lynx) and got the same result.

Upvotes: 41

Answers (12)

TheMagicCow

Reputation: 396

I got the same with a character that visibly appeared as an asterisk, but it was a UTF-8 sequence instead:

Encoder * st;

When compiled, it returned:

g.c:2:1: error: stray ‘\342’ in program
g.c:2:1: error: stray ‘\210’ in program
g.c:2:1: error: stray ‘\227’ in program

342 210 227 turns out to be UTF-8 for ASTERISK OPERATOR (Unicode code point U+2217).

Deleting the '*' and typing it again fixed the problem.

Upvotes: 4

Victor Mwenda

Reputation: 1801

Invalid character in your code.

It is a common copy-paste error, especially when code is copied from Microsoft Word documents or PDF files.

Upvotes: 1

KANJICODER

Reputation: 3885

Sure, convert the file to ASCII and blast all Unicode characters away. It will probably work... But...

You won't know what you fixed.
It will also destroy any Unicode comments. Example: //: A²+B²=C²
It could potentially damage obvious logic and the code will still be broken, but the solution less obvious. For example: A string with "Smart-Quotes" (“ & ”) or a pointer with a full-width asterisk (＊). Now “SOME_THING” looks like a #define (SOME_THING) and ＊SomeType is the wrong type (SomeType).

Two more surgical approaches to fixing the problem:

Switch fonts to see the character. (It might be invisible in your current font)
Regular expression search all Unicode characters not part of non-extended ASCII.

In Notepad++ I can search up to FFFF, which hasn't failed me yet.

[\x{80}-\x{FFFF}]

80 is hex for 128, the first extended ASCII character.

After hitting "find next" and highlighting what appears to be empty space, you can close your search dialog and press Ctrl + C to copy to clipboard.

Then paste the character into a Unicode search tool. I usually use an online one. http://unicode.scarfboy.com/

Example:

I had a bullet point (•) in my code somehow. The Unicode value is 2022 (hex), but when read as ASCII by the compiler you get \342 \200 \242 (3 octal values). It's not as simple as converting each octal values to hex and smashing them together. So "E2 80 A2" is not the hexadecimal Unicode point in your code.

Upvotes: 6

Lukasavicus

Reputation: 154

With me, this error occurred when I copied and pasted code in text format to my editor (gedit).

The code was in a text document (.odt). I copied it and pasted it into gedit.

If you did the same, you have manually rewrite the code.

Upvotes: 0

Agrim Gupta

Reputation: 21

It's perhaps because you copied code from the Internet (from a site which has perhaps not an ASCII encoded page, but a UTF-8 encoded page), so you can convert the code to ASCII from this site:

"http://www.percederberg.net/tools/text_converter.html"

There you can either detect errors manually by converting it back to UTF-8, or you can automatically convert it to ASCII and remove all the stray characters.

Upvotes: 2

visu

Reputation: 21

Whenever the compiler found a special character, it gives these kind of compile errors. The error I found is as follows:

error: stray '\302' in program and error: stray '\240' in program

....

It is some piece of code I copied from a chat messenger. In Facebook Messenger, it was a special character only. After copying into the Vim editor it changed to the correct character only. But the compiler was giving the above error .. then .. that statement I wrote manually after .. it got resolved... :)

Upvotes: 2

Saifu Khan

Reputation: 19

This problem comes when you have copied some text from an HTML page or you have done modification in a Windows environment and are trying to compile in a Unix/Solaris environment.

Please do "dos2unix" to remove the special characters from the file:

dos2unix fileName.ext fileName.ext

Upvotes: 1

ravi

Reputation: 928

The explanations given here are correct. I just wanted to add that this problem might be because you copied the code from somewhere, from a website or a PDF file due to which there are some invalid characters in the code.

Try to find those invalid characters, or just retype the code if you can't. It will definitely compile then.

Source: stray error reason

Upvotes: 0

Eeyore

Reputation: 1

Codo was exactly right on Oct. 5 that &current[i] is the intended text (with the currency symbol inadvertently introduced when the source was put into HTML (see original):

http://downloads.securityfocus.com/vulnerabilities/exploits/59846-1.c

Codo's change makes this exploit code compile without error. I did that and was able to use the exploit on Ubuntu 12.04 (Precise Pangolin) to escalate to root privilege.

Upvotes: 0

Klaus

Reputation: 25643

You have invalid characters in your source. If you don't have any valid non-ASCII characters in your source, maybe in a double quoted string literal, you can simply convert your file back to ASCII with:

tr -cd '\11\12\15\40-\176' < old.c > new.c

The method with iconv will stop at wrong characters which makes no sense. The above command line is working with the example file.

Upvotes: 18

cokedude

Reputation: 387

I noticed an issue in using the above tr command. The tr command COMPLETELY removes the "smart quotes". It would be better to replace the "smart quotes" with something like this.

This will give you a quick preview of what will be replaced.

sed s/[”“]/'"'/g File.txt

This will do the replacements and put the replacement in a new file called WithoutSmartQuotes.txt.

sed s/[”“]/'"'/g File.txt > WithoutSmartQuotes.txt

This will overwrite the original file.

sed -i ".bk" s/[”“]/'"'/g File.txt

http://developmentality.wordpress.com/2010/10/11/how-to-remove-smart-quotes-from-a-text-file/

Upvotes: 0