From: John Hughes <john@Calva.COM>
Date: Tue, 15 May 2001 14:53:43 +0000 (+0000)
Subject: Don\'t run off end of memory in umovestr when USE_PROCFS
X-Git-Tag: v4.5.18~1036
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=aa09c6b01ee425d419cdae4389fad0a06da489ef;p=strace

Don\'t run off end of memory in umovestr when USE_PROCFS
---

diff --git a/ChangeLog b/ChangeLog
index 2d44a465..86c65dac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2001-05-15  John Hughes <john@Calva.COM>
+
+  * util.c: Don't run off the end of valid memory in umovestr when
+    USE_PROCFS.  Important for FREEBSD systems (which seem to have an
+    unmapped page just after the args/env area).
+
 2001-04-18  John Hughes <john@Calva.COM>
 
   * configure.in: test for sys/nscsys.h, the non-stop clusters includes.
diff --git a/util.c b/util.c
index 19a24e48..52911424 100644
--- a/util.c
+++ b/util.c
@@ -632,25 +632,13 @@ char *laddr;
 
 #ifdef USE_PROCFS
 #ifdef HAVE_MP_PROCFS
-	if (pread(tcp->pfd_as, laddr, len, addr) == -1)
-		return -1;
+	int fd = tcp->pfd_as;
 #else
-/*
- * We would like to use pread preferentially for speed
- * but even though SGI has it in their library, it no longer works.
- */
-#ifdef MIPS
-#undef HAVE_PREAD
+	int fd = tcp->pfd;
 #endif
-#ifdef HAVE_PREAD
-	if (pread(tcp->pfd, laddr, len, addr) == -1)
+	lseek(fd, addr, SEEK_SET);
+	if (read(fd, laddr, len) == -1)
 		return -1;
-#else /* !HAVE_PREAD */
-	lseek(tcp->pfd, addr, SEEK_SET);
-	if (read(tcp->pfd, laddr, len) == -1)
-		return -1;
-#endif /* !HAVE_PREAD */
-#endif /* HAVE_MP_PROCFS */
 #endif /* USE_PROCFS */
 
 	return 0;
@@ -668,7 +656,34 @@ int len;
 char *laddr;
 {
 #ifdef USE_PROCFS
-	return umoven(tcp, addr, len, laddr);
+#ifdef HAVE_MP_PROCFS
+	int fd = tcp->pfd_as;
+#else
+	int fd = tcp->pfd;
+#endif
+	/* Some systems (e.g. FreeBSD) can be upset if we read off the
+	   end of valid memory,  avoid this by trying to read up
+	   to page boundaries.  But we don't know what a page is (and
+	   getpagesize(2) (if it exists) doesn't necessarily return
+	   hardware page size).  Assume all pages >= 1024 (a-historical
+	   I know) */
+
+	int page = 1024; 	/* How to find this? */
+	int move = page - (addr & (page - 1));
+	int left = len;
+
+	lseek(fd, addr, SEEK_SET);
+
+	while (left) {
+		if (move > left) move = left;
+		if ((move = read(fd, laddr, move)) == -1)
+			return left != len ? 0 : -1;
+		if (memchr (laddr, 0, move)) break;
+		left -= move;
+		laddr += move;
+		addr += move;
+		move = page;
+	}
 #else /* !USE_PROCFS */
 	int started = 0;
 	int pid = tcp->pid;
@@ -718,8 +733,8 @@ char *laddr;
 
 		addr += sizeof(long), laddr += m, len -= m;
 	}
-	return 0;
 #endif /* !USE_PROCFS */
+	return 0;
 }
 
 #ifdef LINUX