Author: markj
Date: Sun Aug 2 00:18:48 2015
New Revision: 286169
URL: https://svnweb.freebsd.org/changeset/base/286169
Log:
Perform bounds checking when constructing a format string.
This was detected by the FORTIFY_SOURCE build.
PR: 201657
Reported by: pfg
MFC after: 2 weeks
Modified:
head/cddl/contrib/opensolaris/lib/libdtrace/common/dt_printf.c
Modified: head/cddl/contrib/opensolaris/lib/libdtrace/common/dt_printf.c
==============================================================================
--- head/cddl/contrib/opensolaris/lib/libdtrace/common/dt_printf.c Sun Aug
2 00:15:52 2015 (r286168)
+++ head/cddl/contrib/opensolaris/lib/libdtrace/common/dt_printf.c Sun Aug
2 00:18:48 2015 (r286169)
@@ -1348,6 +1348,7 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE
dtrace_aggdesc_t *agg;
caddr_t lim = (caddr_t)buf + len, limit;
char format[64] = "%";
+ size_t ret;
int i, aggrec, curagg = -1;
uint64_t normal;
@@ -1379,7 +1380,9 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE
int prec = pfd->pfd_prec;
int rval;
+ const char *start;
char *f = format + 1; /* skip initial '%' */
+ size_t fmtsz = sizeof(format) - 1;
const dtrace_recdesc_t *rec;
dt_pfprint_f *func;
caddr_t addr;
@@ -1536,6 +1539,7 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE
break;
}
+ start = f;
if (pfd->pfd_flags & DT_PFCONV_ALT)
*f++ = '#';
if (pfd->pfd_flags & DT_PFCONV_ZPAD)
@@ -1548,6 +1552,7 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE
*f++ = '\'';
if (pfd->pfd_flags & DT_PFCONV_SPACE)
*f++ = ' ';
+ fmtsz -= f - start;
/*
* If we're printing a stack and DT_PFCONV_LEFT is set, we
@@ -1558,13 +1563,20 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE
if (func == pfprint_stack && (pfd->pfd_flags & DT_PFCONV_LEFT))
width = 0;
- if (width != 0)
- f += snprintf(f, sizeof (format), "%d", ABS(width));
+ if (width != 0) {
+ ret = snprintf(f, fmtsz, "%d", ABS(width));
+ f += ret;
+ fmtsz = MAX(0, fmtsz - ret);
+ }
- if (prec > 0)
- f += snprintf(f, sizeof (format), ".%d", prec);
+ if (prec > 0) {
+ ret = snprintf(f, fmtsz, ".%d", prec);
+ f += ret;
+ fmtsz = MAX(0, fmtsz - ret);
+ }
- (void) strcpy(f, pfd->pfd_fmt);
+ if (strlcpy(f, pfd->pfd_fmt, fmtsz) >= fmtsz)
+ return (dt_set_errno(dtp, EDT_COMPILER));
pfd->pfd_rec = rec;
if (func(dtp, fp, format, pfd, addr, size, normal) < 0)
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