net: atm: Fix potential Spectre v1

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commit acf784bd0c upstream.

ioc_data.dev_num can be 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:
net/atm/lec.c:702 lec_vcc_attach() warn: potential spectre issue
'dev_lec'

Fix this by sanitizing ioc_data.dev_num before using it to index
dev_lec. Also, notice that there is another instance in which array
dev_lec is being indexed using ioc_data.dev_num at line 705:
lec_vcc_added(netdev_priv(dev_lec[ioc_data.dev_num]),

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>

...

This commit is contained in:

Gustavo A. R. Silva 2018-05-03 13:45:58 -05:00 • committed by Greg Kroah-Hartman

parent 87aa17ca56

commit cc21a60327

1 changed files with 7 additions and 2 deletions

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net/atm/lec.c

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