PS_default_font consists of a buffer value of 51. In our research we found that in function PS_options() in program m, There exists an condition if (ps_params->oldstyle) where the value of ps_params->oldstyle is zero and makes the program enter to the else section, where it calls sprintf() as we observed the basic syntax of sprintf() in this program is sprintf(BUFFERSIZE,char,int). This allows an attacker to cause Denial of Service (Segmentation fault and Memory Corruption) or possibly have unspecified other impacts when a victim opens a specially crafted file. This can be triggered by sending a crafted file to gnuplot.
Sprintf buffer overflow portable#
Gnuplot is a portable command-line driven graphing utility.ĭuring our research on the gnuplot, we found buffer overflow vulnerability. If ((a < INT_MIN / x)) /* `a * x` would underflow */ įor division (except for the INT_MIN and -1 special case), there isn't any possibility of going over INT_MIN or INT_MAX.Buffer overflow vulnerability in PS_options() – gnuplot 5.2.5ĬWE-120: Classic Buffer Overflow Product Details If (a > INT_MAX / x) /* `a * x` would overflow */ If one number is -1 and another is INT_MIN, multiplying them we get abs(INT_MIN) which is 1 higher than INT_MAX There may be a need to check for -1 for two's complement machines. If ((x INT_MAX + x)) /* `a - x` would overflow */ If ((x > 0) & (a > INT_MAX - x)) /* `a + x` would overflow */ With signed integers, once there has been overflow, undefined behaviour (UB) has occurred and your program can do anything (for example: render tests inconclusive). so, at least for C, your point is moot :) By definition, in C (I don't know about C++), unsigned arithmetic does not overflow. I'm not familiar with how good those features are. GCC, for example, has the -fstack-protector.
It should be noted that some compilers can help against these kinds of errors. Since you filled it with, basically, gargabe, the address the CPU jumped to did probably contain byte sequences that, interpreted as program text, cause an invalid memory access (or the address itself was already bad). The run-time error you experience may well be due to an overwritten return address. If you were writing an application that ran under a privileged user account, you'd just have provided an attacker with a first-grade entry to your costumer's system, an ACE hole, if you will. He might use something like the NOP sled technique to have your application start a shell for him. Thereby the attacker mounted a buffer overflow attack. (NB: Better use snprintf if it's available to you). string contains an address of the attacker's choosing at just the point where the uncontrolled sprintf function will overwrite the return address on the stack. |-|īy finding out what exactly the offset between buf and the return address on the stack is, a malicious user may manipulate input to your application in a way that the XXX. Now consider a stack frame of your function. the address of the instruction that is to be executed after the function returns, is pushed to the stack (among other things, typically). (3) When you call a function, the return address, i.e. (2) Strings expect the characters belonging to that string to be stored so that character n+1 is stored after character n. the smaller the addresses, the more the stack is filled. (1) Your stack typically "grows" backwards, i.e. comes from uncontrolled sources, you are very close to generating a buffer overflow vulnerability. And what physically happens next, may well be a major security hole. However, the world does not stop simply because someone did not define what exactly should happen next. As other posters have noted, it invokes UB. It makes a lot of sense to consider what happens in your and, more importantly, similar, cases.
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