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Message-ID: <CAGUWgD8zb-UEWp8TVHDSbo=iaCU4gWqnJHCFSPiR0fQWS73gPg@mail.gmail.com>
Date: Tue, 7 Feb 2023 16:45:16 +0200
From: Georgi Guninski <gguninski@...il.com>
To: oss-security@...ts.openwall.com
Subject: SEGV in `alloca(BIG)` and `long pl[BIG]`

Hi v3nd0rz crowd.

Inline are two C warez, which crash on
`alloca(BIG)` and `long pl[BIG]`.

I think alloca(BIG) should return error if BIG>max_signed_size_t.
In C++ `new[BUG]` throws exception and core dumps.

===
#include <stdlib.h>
#include <stdio.h>
#include <alloca.h>
/*
 * Author:  Georgi Guninski
 * CV: https://j.ludost.net/resumegg.pdf
[joro@...ora prim]$ gcc alloca1.c
[joro@...ora prim]$ ./a.out -1
calloc=(nil) alloca()=0x7fff66c931e0
Segmentation fault (core dumped)

[joro@...ora prim]$ ./a.out 4611686018427387904
Bus error (core dumped)
 */
int main(int ac, char **av) {
    void *p;
    size_t l,cou;
    l=atol(av[1]);
    p=calloc(l,l);
    char *pl=alloca(l);
    printf("calloc=%p alloca()=%p\n",p,pl);
    if (pl) {
        for(cou=0;cou<l;cou++)
            pl[cou]=0xcc;
    }
    return(0);
}
===

#include <stdlib.h>
#include <stdio.h>
/*
 * calloc1.c
 *  * Author:  Georgi Guninski
 * CV: https://j.ludost.net/resumegg.pdf
[joro@...ora prim]$ gcc calloc1.c
[joro@...ora prim]$ ./a.out -1
calloc=(nil) long[l]=0x7ffe33f7e930
Segmentation fault (core dumped)
 * */
int main(int ac, char **av) {
    void *p;
    size_t l,cou;
    l=atol(av[1]);
    p=calloc(l,l);
    long pl[l];
    printf("calloc=%p long[l]=%p\n",p,pl);
    if (pl) {
        for(cou=0;cou<l;cou++)
            pl[cou]=0xcafebabe;
    }
    return(0);
}
===

===

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