net: cxgb3_main: fix potential Spectre v1
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Tue, 17 Jul 2018 01:59:58 +0000 (20:59 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 22 Jul 2018 12:27:39 +0000 (14:27 +0200)
commit53e795c755de6e20516ae4387b78c4d92f841e2b
tree758c0bae0ed4b38f3e4ca3a6f8b69d311db01dce
parent224d2337c000090fca8e364e9e7b616c2f67adda
net: cxgb3_main: fix potential Spectre v1

commit 676bcfece19f83621e905aa55b5ed2d45cc4f2d3 upstream.

t.qset_idx can be indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c:2286 cxgb_extension_ioctl()
warn: potential spectre issue 'adapter->msix_info'

Fix this by sanitizing t.qset_idx before using it to index
adapter->msix_info

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c