diff options
Diffstat (limited to 'source3')
| -rw-r--r-- | source3/lib/util_str.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/source3/lib/util_str.c b/source3/lib/util_str.c index 070c59c1b2..924cf9d921 100644 --- a/source3/lib/util_str.c +++ b/source3/lib/util_str.c @@ -430,6 +430,27 @@ BOOL str_is_all(const char *s,char c) return True; } + +/** + * In developer builds, clobber a region of memory. + * + * If we think a string buffer is longer than it really is, this ought + * to make the failure obvious, by segfaulting (if in the heap) or by + * killing the return address (on the stack), or by trapping under a + * memory debugger. + * + * This is meant to catch possible string overflows, even if the + * actual string copied is not big enough to cause an overflow. + **/ +void clobber_region(char *dest, size_t len) +{ +#ifdef DEVELOPER + /* F1 is odd and 0xf1f1f1f1 shouldn't be a valid pointer */ + memset(dest, 0xF1, len); +#endif +} + + /** Safe string copy into a known length string. maxlength does not include the terminating zero. @@ -444,13 +465,7 @@ char *safe_strcpy(char *dest,const char *src, size_t maxlength) return NULL; } -#ifdef DEVELOPER - /* We intentionally write out at the extremity of the destination - * string. If the destination is too short (e.g. pstrcpy into mallocd - * or fstring) then this should cause an error under a memory - * checker. */ - dest[maxlength] = '\0'; -#endif + clobber_region(dest, maxlength+1); if (!src) { *dest = 0; @@ -490,6 +505,8 @@ char *safe_strcat(char *dest, const char *src, size_t maxlength) src_len = strlen(src); dest_len = strlen(dest); + clobber_region(dest + dest_len, maxlength + 1 - dest_len); + if (src_len + dest_len > maxlength) { DEBUG(0,("ERROR: string overflow by %d in safe_strcat [%.50s]\n", (int)(src_len + dest_len - maxlength), src)); @@ -499,7 +516,7 @@ char *safe_strcat(char *dest, const char *src, size_t maxlength) dest[maxlength] = 0; return NULL; } - + memcpy(&dest[dest_len], src, src_len); dest[dest_len + src_len] = 0; return dest; @@ -516,6 +533,8 @@ char *alpha_strcpy(char *dest, const char *src, const char *other_safe_chars, si { size_t len, i; + clobber_region(dest, maxlength); + if (!dest) { DEBUG(0,("ERROR: NULL dest in alpha_strcpy\n")); return NULL; @@ -554,8 +573,12 @@ char *alpha_strcpy(char *dest, const char *src, const char *other_safe_chars, si char *StrnCpy(char *dest,const char *src,size_t n) { char *d = dest; + + clobber_region(dest, n+1); + if (!dest) return(NULL); + if (!src) { *dest = 0; return(dest); @@ -576,6 +599,8 @@ char *strncpyn(char *dest, const char *src, size_t n, char c) char *p; size_t str_len; + clobber_region(dest, n+1); + p = strchr_m(src, c); if (p == NULL) { DEBUG(5, ("strncpyn: separator character (%c) not found\n", c)); |