Wireshark · Wireshark-bugs: [Wireshark-bugs] [Bug 8722] New: ASN.1 aligned PER dissector fails to check return value of g_malloc

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Bug ID	8722
Summary	ASN.1 aligned PER dissector fails to check return value of g_malloc()
Classification	Unclassified
Product	Wireshark
Version	1.11.x (Experimental)
Hardware	x86
OS	All
Status	UNCONFIRMED
Severity	Major
Priority	Low
Component	Dissection engine (libwireshark)
Assignee	bugzilla-admin@wireshark.org
Reporter	otr@bockcay.de

Build Information:

--
The "dissect_per_restricted_character_string_sorted()" function ins
packet-per.c fails to check the return value of g_malloc() in line 638:

    buf = (guint8 *)g_malloc(length+1);
    old_offset=offset;

If a large value for the length variable is set e.g 0xffffffff, the malloc
fails and the application crashes with a segmentation fault (invalid write,
tested on Linux).

This may result in a write to the address 0x00000000 later in the same function
at multiple locations (assignments to buf):

        if((bits_per_char==8) || (alphabet==NULL)){
here ->         buf[char_pos]=val;
        } else {
            if (val < alphabet_length){
here ->                buf[char_pos]=alphabet[val];
            } else {
here ->             buf[char_pos] = '?';    /* XXX - how to mark this? */
            }
        }

This bug was found by fuzzing the ULP protocol against the latest git version
of Wireshark.

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