Date: Tue, 10 Feb 2009 22:57:39 +0100 From: Roman Divacky <rdivacky@freebsd.org> To: net@freebsd.org Cc: mav@freebsd.org Subject: unsafe C in netgraph/pppoed.c Message-ID: <20090210215739.GA24102@freebsd.org>
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hi
struct pppoe_tag {
u_int16_t tag_type;
u_int16_t tag_len;
char tag_data[];
}__packed;
struct pppoe_hdr{
u_int8_t ver:4;
u_int8_t type:4;
u_int8_t code;
u_int16_t sid;
u_int16_t length;
struct pppoe_tag tag[];
}__packed;
this is inherently unsafe as the tag_data can only have 0 elements
to be used safely. gcc compiles this without warning although there
should be a big one.
I found this using clang, which produces this error/warning:
lev pppoed$ ccc -c pppoed.c ccc: Unknown host 'freebsd', using generic host information.
In file included from pppoed.c:41:
/usr/include/netgraph/ng_pppoe.h:213:22: error: 'struct pppoe_tag' may not be used as an array element due to flexible array member
struct pppoe_tag tag[];
^
1 diagnostic generated.
can you guys take a look at this issue?
thnx!
roman
p.s. please keep me CCed as I am not subscribed to net@
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