[Bug 206761] Kernel stack overflow in sysctl handler for kern.binmisc.add

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206761

Sean Bruno <sbruno at FreeBSD.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|New                         |In Progress
                 CC|                            |sbruno at FreeBSD.org

--- Comment #8 from Sean Bruno <sbruno at FreeBSD.org> ---
Something like this has been suggested by sson@ to resolve these issues.  What
do you guys think?

diff --git a/sys/kern/imgact_binmisc.c b/sys/kern/imgact_binmisc.c
index dd57717..39ca156 100644
--- a/sys/kern/imgact_binmisc.c
+++ b/sys/kern/imgact_binmisc.c
@@ -1,5 +1,5 @@
/*-
- * Copyright (c) 2013-15, Stacey D. Son
+ * Copyright (c) 2013-16, Stacey D. Son
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
@@ -220,16 +220,17 @@ imgact_binmisc_add_entry(ximgact_binmisc_entry_t *xbe)
{
        imgact_binmisc_entry_t *ibe;
        char *p;
+       int cnt;

        if (xbe->xbe_msize > IBE_MAGIC_MAX)
                return (EINVAL);

-       for(p = xbe->xbe_name; *p != 0; p++)
-               if (!isascii((int)*p))
+       for(cnt = 0, p = xbe->xbe_name; *p != 0; cnt++, p++)
+               if (cnt >= IBE_NAME_MAX || !isascii((int)*p))
                        return (EINVAL);

-       for(p = xbe->xbe_interpreter; *p != 0; p++)
-               if (!isascii((int)*p))
+       for(cnt = 0, p = xbe->xbe_interpreter; *p != 0; cnt++, p++)
+               if (cnt >= IBE_INTERP_LEN_MAX || !isascii((int)*p))
                        return (EINVAL);

        /* Make sure we don't have any invalid #'s. */
@@ -266,8 +267,6 @@ imgact_binmisc_add_entry(ximgact_binmisc_entry_t *xbe)

        /* Preallocate a new entry. */
        ibe = imgact_binmisc_new_entry(xbe);
-       if (!ibe)
-               return (ENOMEM);

        SLIST_INSERT_HEAD(&interpreter_list, ibe, link);
        interp_list_entry_count++;

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