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Perform bounds checking when constructing a format string.

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This was detected by the FORTIFY_SOURCE build.

PR:		201657
Reported by:	pfg
MFC after:	2 weeks
This commit is contained in:
Mark Johnston 2015-08-02 00:18:48 +00:00
parent 70e47040b0
commit 61ab25cd3d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=286169
1 changed files with 17 additions and 5 deletions
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22
cddl/contrib/opensolaris/lib/libdtrace/common/dt_printf.c
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@ -1348,6 +1348,7 @@ dt_printf_format(dtrace_hdl_t *dtp, FILE *fp, const dt_pfargv_t *pfv,
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 *fp, const dt_pfargv_t *pfv,
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 *fp, const dt_pfargv_t *pfv,
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 *fp, const dt_pfargv_t *pfv,
*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 *fp, const dt_pfargv_t *pfv,
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)