> On Oct 13, 2017, at 11:01 AM, Aaron Eppert <[email protected]>
> wrote:
>
> Justin,
>
> Indeed, cutting new territory is always interesting. As for the code,
>
> https://github.com/aeppert/test_file_analyzer
>
>
> File I am using for this case:
> https://www.bro.org/static/exchange-2013/faf-exercise.pcap
>
> `bro -C -r faf-exercise.pcap` after building and installing the plugin.
>
> My suspicion is it’s either unbelievably trivial and I keep missing it
> because I am the only one staring at it, or it’s a rather deep rabbit hole.
>
> Aaron
Thanks for putting that together.. now I see what you mean. Building the plugin
with ASAN confirms it is trying to access uninitialized memory:
$ /usr/local/bro/bin/bro -C -r faf-exercise.pcap
TEST::Finalize total_len = 65960
BUFFER
00 ea 09 00 50 61 00 00 80 eb 09 00 50 61 00 00
=================================================================
==93650==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x603000bf5d08 at pc 0x00010b19d39b bp 0x7fff57829e10 sp 0x7fff57829e08
READ of size 1 at 0x603000bf5d08 thread T0
#0 0x10b19d39a in print_bytes(std::__1::basic_ostream<char,
std::__1::char_traits<char> >&, char const*, unsigned char const*, unsigned
long, bool) TEST.cc:21
#1 0x10b19e43b in file_analysis::TEST::Finalize() TEST.cc:87
...
The problem is this line:
bufv->push_back(data);
That's only pushing the first char of the buffer onto the vector, not the
entire buffer.
If you print out bufv->size() you'll see that it is not what it should be.
If you apply this change it will run without crashing and I believe give the
expected output:
diff --git a/src/TEST.cc b/src/TEST.cc
index 8d78ef2..56d0a83 100644
--- a/src/TEST.cc
+++ b/src/TEST.cc
@@ -56,7 +56,7 @@ bool TEST::DeliverStream(const u_char* data, uint64 len)
}
if ( total_len < TEST_MAX_BUFFER) {
- bufv->push_back(data);
+ print_bytes(std::cout, "BUFFER", data, len);
total_len += len;
}
@@ -84,7 +84,7 @@ void TEST::Finalize()
//auto pos = std::find(bufv->begin(), bufv->end(), (unsigned char
*)"Exif");
//std::cout << "Offset = " << std::distance( bufv->begin(), pos ) <<
std::endl;
- print_bytes(std::cout, "BUFFER", (const u_char *)&bufv[0], total_len);
+ //print_bytes(std::cout, "BUFFER", (const u_char *)&bufv[0], total_len);
val_list* vl = new val_list();
vl->append(GetFile()->GetVal()->Ref());
I don't know off the top of my head the right way to extend a c++ vector by a c
buffer, but doing so should fix things.
—
Justin Azoff
_______________________________________________
bro-dev mailing list
[email protected]
http://mailman.icsi.berkeley.edu/mailman/listinfo/bro-dev
