svn commit: r366656 - head/sys/kern

[Warner Losh]

Author: imp
Date: Mon Oct 12 22:07:44 2020
New Revision: 366656
URL: https://svnweb.freebsd.org/changeset/base/366656

Log:
  newbus: use ssize_t to match sb's len and size, fix ordering of space check
  
  Both s_len and s_size are ssize_t, so their differece is also more
  properly a ssize_t not a size_t. Also, assert that len is <= size when
  we enter. This should always be the case. Ensure that we have that one
  byte that we write to the end of the buffer before we do so, though
  the error should already be set on the buffer if not, and the only
  times we supply 'partial' buffers they should be plenty large.
  
  Reviewed by: cem, jhb (prior version, I did cem's suggestion)
  Differential Revsion: https://reviews.freebsd.org/D26752

Modified:
  head/sys/kern/subr_bus.c

Modified: head/sys/kern/subr_bus.c
==============================================================================
--- head/sys/kern/subr_bus.c	Mon Oct 12 21:35:29 2020	(r366655)
+++ head/sys/kern/subr_bus.c	Mon Oct 12 22:07:44 2020	(r366656)
@@ -4956,18 +4956,19 @@ static int
 bus_child_pnpinfo_sb(device_t dev, struct sbuf *sb)
 {
 	char *p;
-	size_t space;
+	ssize_t space;
 
 	MPASS((sb->s_flags & SBUF_INCLUDENUL) == 0);
+	MPASS(sb->s_size >= sb->s_len);
 	if (sb->s_error != 0)
 		return (-1);
-	p = EOB(sb);
-	*p = '\0';	/* sbuf buffer isn't NUL terminated until sbuf_finish() */
 	space = SPACE(sb);
 	if (space <= 1) {
 		sb->s_error = ENOMEM;
 		return (-1);
 	}
+	p = EOB(sb);
+	*p = '\0';	/* sbuf buffer isn't NUL terminated until sbuf_finish() */
 	bus_child_pnpinfo_str(dev, p, space);
 	sb->s_len += strlen(p);
 	return (0);
@@ -4985,18 +4986,19 @@ static int
 bus_child_location_sb(device_t dev, struct sbuf *sb)
 {
 	char *p;
-	size_t space;
+	ssize_t space;
 
 	MPASS((sb->s_flags & SBUF_INCLUDENUL) == 0);
+	MPASS(sb->s_size >= sb->s_len);
 	if (sb->s_error != 0)
 		return (-1);
-	p = EOB(sb);
-	*p = '\0';	/* sbuf buffer isn't NUL terminated until sbuf_finish() */
 	space = SPACE(sb);
 	if (space <= 1) {
 		sb->s_error = ENOMEM;
 		return (-1);
 	}
+	p = EOB(sb);
+	*p = '\0';	/* sbuf buffer isn't NUL terminated until sbuf_finish() */
 	bus_child_location_str(dev, p, space);
 	sb->s_len += strlen(p);
 	return (0);