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proc/escape.c: Make sure all escape*() arguments are safe.

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The SECURE_ESCAPE_ARGS() macro solves several potential problems
(although we found no problematic calls to the escape*() functions in
procps's code-base, but had to thoroughly review every call; and this is
library code):

1/ off-by-one overflows if the size of the destination buffer is 0;

2/ buffer overflows if this size (or "maxroom") is negative;

3/ integer overflows (for example, "*maxcells+1");

4/ always null-terminate the destination buffer (unless its size is 0).
This commit is contained in:
Qualys Security Advisory 1970-01-01 00:00:00 +00:00 committed by Craig Small
parent 00ab5f0b32
commit 47303a3592
1 changed files with 19 additions and 0 deletions
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19
proc/escape.c
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@ -20,6 +20,7 @@
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <limits.h>
#include "procps.h"
#include "escape.h"
#include "readproc.h"
@ -32,12 +33,22 @@
# include <langinfo.h>
#endif
#define SECURE_ESCAPE_ARGS(dst, bytes, cells) do { \
if ((bytes) <= 0) return 0; \
*(dst) = '\0'; \
if ((bytes) >= INT_MAX) return 0; \
if ((cells) >= INT_MAX) return 0; \
if ((cells) <= 0) return 0; \
} while (0)
#if (__GNU_LIBRARY__ >= 6) && (!defined(__UCLIBC__) || defined(__UCLIBC_HAS_WCHAR__))
static int escape_str_utf8(char *restrict dst, const char *restrict src, int bufsize, int *maxcells){
int my_cells = 0;
int my_bytes = 0;
mbstate_t s;
SECURE_ESCAPE_ARGS(dst, bufsize, *maxcells);
memset(&s, 0, sizeof (s));
for(;;) {
@ -146,6 +157,7 @@ int escape_str(char *restrict dst, const char *restrict src, int bufsize, int *m
}
#endif
SECURE_ESCAPE_ARGS(dst, bufsize, *maxcells);
if(bufsize > *maxcells+1) bufsize=*maxcells+1; // FIXME: assumes 8-bit locale
for(;;){
@ -172,6 +184,8 @@ int escape_str(char *restrict dst, const char *restrict src, int bufsize, int *m
int escape_strlist(char *restrict dst, char *restrict const *restrict src, size_t bytes, int *cells){
size_t i = 0;
SECURE_ESCAPE_ARGS(dst, bytes, *cells);
for(;;){
i += escape_str(dst+i, *src, bytes-i, cells);
if(bytes-i < 3) break; // need room for space, a character, and the NUL
@ -190,6 +204,8 @@ int escape_command(char *restrict const outbuf, const proc_t *restrict const pp,
int overhead = 0;
int end = 0;
SECURE_ESCAPE_ARGS(outbuf, bytes, *cells);
if(flags & ESC_ARGS){
char **lc = (char**)pp->cmdline;
if(lc && *lc) return escape_strlist(outbuf, lc, bytes, cells);
@ -231,7 +247,10 @@ int escape_command(char *restrict const outbuf, const proc_t *restrict const pp,
// using the traditional escape.h calling conventions
int escaped_copy(char *restrict dst, const char *restrict src, int bufsize, int *maxroom){
int n;
SECURE_ESCAPE_ARGS(dst, bufsize, *maxroom);
if (bufsize > *maxroom+1) bufsize = *maxroom+1;
n = snprintf(dst, bufsize, "%s", src);
if (n >= bufsize) n = bufsize-1;
*maxroom -= n;