Date: Sat, 9 May 2020 15:56:02 +0000 (UTC) From: Ed Maste <emaste@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r360849 - in head: share/man/man9 sys/kern Message-ID: <202005091556.049Fu2Vp051746@repo.freebsd.org>
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Author: emaste Date: Sat May 9 15:56:02 2020 New Revision: 360849 URL: https://svnweb.freebsd.org/changeset/base/360849 Log: remove %n support from printf(9) It can be dangerous and there is no need for it in the kernel. Inspired by Kees Cook's change in Linux, and later OpenBSD. Reviewed by: cem, gordon, philip Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D24760 Modified: head/share/man/man9/printf.9 head/sys/kern/subr_prf.c Modified: head/share/man/man9/printf.9 ============================================================================== --- head/share/man/man9/printf.9 Sat May 9 14:49:56 2020 (r360848) +++ head/share/man/man9/printf.9 Sat May 9 15:56:02 2020 (r360849) @@ -26,7 +26,7 @@ .\" .\" $FreeBSD$ .\" -.Dd November 18, 2015 +.Dd May 9, 2020 .Dt PRINTF 9 .Os .Sh NAME @@ -83,7 +83,7 @@ parameter in the same manner as .Xr printf 3 . However, .Xr printf 9 -adds two other conversion specifiers. +adds two other conversion specifiers and omits one. .Pp The .Cm \&%b @@ -119,6 +119,10 @@ a time. The string is used as a delimiter between individual bytes. If present, a width directive will specify the number of bytes to display. By default, 16 bytes of data are output. +.Pp +The +.Cm \&%n +conversion specifier is not supported. .Pp The .Fn log Modified: head/sys/kern/subr_prf.c ============================================================================== --- head/sys/kern/subr_prf.c Sat May 9 14:49:56 2020 (r360848) +++ head/sys/kern/subr_prf.c Sat May 9 15:56:02 2020 (r360849) @@ -775,20 +775,24 @@ reswitch: switch (ch = (u_char)*fmt++) { lflag = 1; goto reswitch; case 'n': + /* + * We do not support %n in kernel, but consume the + * argument. + */ if (jflag) - *(va_arg(ap, intmax_t *)) = retval; + (void)va_arg(ap, intmax_t *); else if (qflag) - *(va_arg(ap, quad_t *)) = retval; + (void)va_arg(ap, quad_t *); else if (lflag) - *(va_arg(ap, long *)) = retval; + (void)va_arg(ap, long *); else if (zflag) - *(va_arg(ap, size_t *)) = retval; + (void)va_arg(ap, size_t *); else if (hflag) - *(va_arg(ap, short *)) = retval; + (void)va_arg(ap, short *); else if (cflag) - *(va_arg(ap, char *)) = retval; + (void)va_arg(ap, char *); else - *(va_arg(ap, int *)) = retval; + (void)va_arg(ap, int *); break; case 'o': base = 8;
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