uml: improved error handling while locating temp dir

* arch/um/os-Linux/mem.c (make_tempfile): Don't deref NULL upon failed malloc.

* arch/um/os-Linux/mem.c (make_tempfile): Handle NULL tempdir.
Don't let a long tempdir (e.g., via TMPDIR) provoke heap corruption.

[ jdike - formatting cleanups, deleted obsolete comment ]

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 38742c21def52499788ad6175674d1b6db0162fa..93a11d7edfa0505a7acfd9bd99a0266aec97f933 100644 (file)
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -162,11 +162,6 @@ found:
        goto out;
 }
 
-/*
- * This proc still used in tt-mode
- * (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger).
- * So it isn't 'static' yet.
- */
 static int __init make_tempfile(const char *template, char **out_tempname,
                                int do_unlink)
 {
@@ -175,10 +170,13 @@ static int __init make_tempfile(const char *template, char **out_tempname,
 
        which_tmpdir();
        tempname = malloc(MAXPATHLEN);
-       if (!tempname)
-               goto out;
+       if (tempname == NULL)
+               return -1;
 
        find_tempdir();
+       if ((tempdir == NULL) || (strlen(tempdir) >= MAXPATHLEN))
+               return -1;
+
        if (template[0] != '/')
                strcpy(tempname, tempdir);
        else
@@ -196,9 +194,8 @@ static int __init make_tempfile(const char *template, char **out_tempname,
        }
        if (out_tempname) {
                *out_tempname = tempname;
-       } else {
+       } else
                free(tempname);
-       }
        return fd;
 out:
        free(tempname);