d/freebsd-nq
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While convenient, avoid using alloca() for reasons specified in

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the BUGS section of the alloca(3) manpage.  In particular, when
the number of TCP sockets is several tens of thousand, trying to
"sysctl -a" would SIGSEGV on the net.inet.tcp.pcblist entry (it
would exceed the stacksize ulimit, in an undetectable manner).

Reported by:	Igor Sysoev
This commit is contained in:
Ruslan Ermilov 2006-09-06 20:15:43 +00:00
parent 14ca3cd6ff
commit ccf2597759
1 changed files with 20 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
sbin/sysctl/sysctl.c
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@ -541,7 +541,7 @@ oidfmt(int *oid, int len, char *fmt, u_int *kind)
static int
show_var(int *oid, int nlen)
{
u_char buf[BUFSIZ], *val, *p;
u_char buf[BUFSIZ], *val, *oval, *p;
char name[BUFSIZ], *fmt, *sep;
int qoid[CTL_MAXNAME+2];
int i;
@ -584,14 +584,21 @@ show_var(int *oid, int nlen)
i = sysctl(oid, nlen, 0, &j, 0, 0);
j += j; /* we want to be sure :-) */
val = alloca(j + 1);
val = oval = malloc(j + 1);
if (val == NULL) {
warnx("malloc failed");
return (-1);
}
len = j;
i = sysctl(oid, nlen, val, &len, 0, 0);
if (i || !len)
if (i || !len) {
free(oval);
return (1);
}
if (bflag) {
fwrite(val, 1, len, stdout);
free(oval);
return (0);
}
val[len] = '\0';
@ -603,6 +610,7 @@ show_var(int *oid, int nlen)
if (!nflag)
printf("%s%s", name, sep);
printf("%.*s", len, p);
free(oval);
return (0);
case 'I':
@ -630,6 +638,7 @@ show_var(int *oid, int nlen)
len -= sizeof(int);
p += sizeof(int);
}
free(oval);
return (0);
case 'L':
@ -657,12 +666,14 @@ show_var(int *oid, int nlen)
len -= sizeof(long);
p += sizeof(long);
}
free(oval);
return (0);
case 'P':
if (!nflag)
printf("%s%s", name, sep);
printf("%p", *(void **)p);
free(oval);
return (0);
case 'T':
@ -683,12 +694,15 @@ show_var(int *oid, int nlen)
if (func) {
if (!nflag)
printf("%s%s", name, sep);
free(oval);
return ((*func)(len, p));
}
/* FALLTHROUGH */
default:
if (!oflag && !xflag)
if (!oflag && !xflag) {
free(oval);
return (1);
}
if (!nflag)
printf("%s%s", name, sep);
printf("Format:%s Length:%d Dump:0x", fmt, len);
@ -696,8 +710,10 @@ show_var(int *oid, int nlen)
printf("%02x", *p++);
if (!xflag && len > 16)
printf("...");
free(oval);
return (0);
}
free(oval);
return (1);
}