Vulnerability CVE-2024-46679
Published: 2024-09-13

Description:
In the Linux kernel, the following vulnerability has been resolved:

ethtool: check device is present when getting link settings

A sysfs reader can race with a device reset or removal, attempting to
read device state when the device is not actually present. eg:

[exception RIP: qed_get_current_link+17]
#8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede]
#9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3
#10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4
#11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300
#12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c
#13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b
#14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3
#15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1
#16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f
#17 [ffffb9e4f2907f38] do_syscall_64 at ffffffff98a052fb

crash> struct net_device.state ffff9a9d21336000
state = 5,

state 5 is __LINK_STATE_START (0b1) and __LINK_STATE_NOCARRIER (0b100).
The device is not present, note lack of __LINK_STATE_PRESENT (0b10).

This is the same sort of panic as observed in commit 4224cfd7fb65
("net-sysfs: add check for netdevice being present to speed_show").

There are many other callers of __ethtool_get_link_ksettings() which
don't have a device presence check.

Move this check into ethtool to protect all callers.

 References:
https://git.kernel.org/stable/c/ec7b4f7f644018ac293cb1b02528a40a32917e62
https://git.kernel.org/stable/c/842a40c7273ba1c1cb30dda50405b328de1d860e
https://git.kernel.org/stable/c/7a8d98b6d6484d3ad358510366022da080c37cbc
https://git.kernel.org/stable/c/9bba5955eed160102114d4cc00c3d399be9bdae4
https://git.kernel.org/stable/c/94ab317024ba373d37340893d1c0358638935fbb
https://git.kernel.org/stable/c/1d6d9b5b1b95bfeccb84386a51b7e6c510ec13b2
https://git.kernel.org/stable/c/a699781c79ecf6cfe67fb00a0331b4088c7c8466
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