[U-Boot] Bug in netconsole?
Joe Hershberger
joe.hershberger at gmail.com
Fri Nov 16 05:41:17 CET 2012
Hi Nick,
On Wed, Nov 14, 2012 at 3:59 AM, Nick Thompson <nick.thompson at ge.com> wrote:
> I think there might be a bug in this commit:
>
> http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commitdiff;h=2c8fe5120f8da013cbd789be2f10cce880972836
>
> The commit makes "the netconsole buffer size configurable". It adds CONFIG_NETCONSOLE_BUFFER_SIZE and maintains the original 512 default value used to define the length of input_buffer[]. nc_input_packet uses sizeof this to read packet data into input_buffer[]. This appears fine.
>
> The commit also adds to following in the output chain:
>
> @@ -214,7 +218,7 @@ static void nc_puts(const char *s)
>
> len = strlen(s);
> while (len) {
> - int send_len = min(len, 512);
> + int send_len = min(len, sizeof(input_buffer));
> nc_send_packet(s, send_len);
> len -= send_len;
> s += send_len;
>
> I can't see how this code relates to the sizeof input_buffer. The nc_puts data is written directly into NetTxPacket (plus header offsets) which is set to 1536 + alignment bytes long. If input_buffer is bigger than this, a buffer overflow will occur. Obviously the default value of 512 will not trigger the problem. The 512 magic number possibly ought to be derived from PKTSIZE_ALIGN (net.h), but I don't think sizeof(input_buffer) is appropriate here.
I agree with your assessment based on this email (though I haven't dug
into the code yet to fix it). Thanks for the report.
-Joe
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