On Thu, 2013-10-31 at 15:26 +0330, hamid alaei wrote: > Hi everyone, > Assume there is a C code that do this: > > > char buff1[20]; > char buff2[30]="some small string"; > ... > > strcpy(buff1, buff2); > > > > This code is can be regarded unsafe not only because it use strcpy(), > which doesn't accept a size argument for the maximum capacity of > buff1, but also because the maximum capacity if the target string > buff1 is less than the maximum capacity of the src string buff2. > > I know that if strcpy() tries to write outside buff1, then memcheck or > sgcheck can detect that, depending on whether these strings are in > stack/global memory or in the heap. But I want a warning while calling > strcpy() in this manner as well, regardless of whether overflow > happens or not. > > > I am wondering if there is such a tool to do so. I guess it should > replace strcpy() and similar functions with a wrapper. Does anybody > know suck a tool/extension or how to write such a wrapper that can > have access to the max-size of buff1 and buff2?
This might be an interesting addition to e.g. memcheck (or other tools that are replacing str* and others functions). I think this will be relatively easy to do for "simple cases" of stack and global arrays, and maybe arrays in a stack/global struct : using --read-var-info=yes, valgrind provides access to (some) information about theses, (and from a small experiment, it looks like it knows the size of these). However, for more complex cases (e.g. arrays in a dynamically allocated struct), this will be more complex: how to guess (or keep track) that a pointer inside a block is a pointer to an array smaller than the malloc-ed block is unclear to me. Philippe ------------------------------------------------------------------------------ Android is increasing in popularity, but the open development platform that developers love is also attractive to malware creators. Download this white paper to learn more about secure code signing practices that can help keep Android apps secure. http://pubads.g.doubleclick.net/gampad/clk?id=65839951&iu=/4140/ostg.clktrk _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
