From: Nikolay Aleksandrov Date: Wed, 23 Oct 2013 13:04:49 +0000 (+0200) Subject: netconsole: fix NULL pointer dereference X-Git-Tag: omap-for-v3.13/fixes-for-merge-window-take2~67^2~31 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=45e526e80e6fdc796d3bc05716d5c930a427df4d;p=pandora-kernel.git netconsole: fix NULL pointer dereference We need to disable the netconsole (enabled = 0) before setting nt->np.dev to NULL because otherwise we might still have users after the netpoll_cleanup() since nt->enabled is set afterwards and we can have a message which will result in a NULL pointer dereference. It is very easy to hit dereferences all over the netpoll_send_udp function by running the following two loops in parallel: while [ 1 ]; do echo 1 > enabled; echo 0 > enabled; done; while [ 1 ]; do echo 00:11:22:33:44:55 > remote_mac; done; (the second loop is to generate messages, it can be done by anything) We're safe to set nt->np.dev = NULL and nt->enabled = 0 with the spinlock since it's required in the write_msg() function. Signed-off-by: Nikolay Aleksandrov Reviewed-by: Veacelsav Falico Signed-off-by: David S. Miller --- Reading git-diff-tree failed