Eric Dumazet c8775b97bf netrom: fix info-leak in nr_write_internal() ... [ Upstream commit 31642e7089 ] Simon Kapadia reported the following issue: <quote> The Online Amateur Radio Community (OARC) has recently been experimenting with building a nationwide packet network in the UK. As part of our experimentation, we have been testing out packet on 300bps HF, and playing with net/rom. For HF packet at this baud rate you really need to make sure that your MTU is relatively low; AX.25 suggests a PACLEN of 60, and a net/rom PACLEN of 40 to go with that. However the Linux net/rom support didn't work with a low PACLEN; the mkiss module would truncate packets if you set the PACLEN below about 200 or so, e.g.: Apr 19 14:00:51 radio kernel: [12985.747310] mkiss: ax1: truncating oversized transmit packet! This didn't make any sense to me (if the packets are smaller why would they be truncated?) so I started investigating. I looked at the packets using ethereal, and found that many were just huge compared to what I would expect. A simple net/rom connection request packet had the request and then a bunch of what appeared to be random data following it: </quote> Simon provided a patch that I slightly revised: Not only we must not use skb_tailroom(), we also do not want to count NR_NETWORK_LEN twice. Fixes: 1da177e4c3 ("Linux-2.6.12-rc2") Co-Developed-by: Simon Kapadia <szymon@kapadia.pl> Signed-off-by: Simon Kapadia <szymon@kapadia.pl> Signed-off-by: Eric Dumazet <edumazet@google.com> Tested-by: Simon Kapadia <szymon@kapadia.pl> Reviewed-by: Simon Horman <simon.horman@corigine.com> Link: https://lore.kernel.org/r/20230524141456.1045467-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-06-09 10:32:16 +02:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
af_netrom.c	netrom: Fix use-after-free caused by accept on already connected socket	2023-02-09 11:26:36 +01:00
nr_dev.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152	2019-05-30 11:26:32 -07:00
nr_in.c	net: netrom: nr_in: Remove redundant assignment to ns	2021-04-28 13:59:08 -07:00
nr_loopback.c	net: Remove redundant if statements	2021-08-05 13:27:50 +01:00
nr_out.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152	2019-05-30 11:26:32 -07:00
nr_route.c	net: Remove redundant if statements	2021-08-05 13:27:50 +01:00
nr_subr.c	netrom: fix info-leak in nr_write_internal()	2023-06-09 10:32:16 +02:00
nr_timer.c	netrom: Fix use-after-free of a listening socket.	2023-02-01 08:27:27 +01:00
sysctl_net_netrom.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152	2019-05-30 11:26:32 -07:00