hwmon: (k10temp) Check return value of amd_smn_read()

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[ Upstream commit c2d79cc545 ]

Check the return value of amd_smn_read() before saving a value. This
ensures invalid values aren't saved or used.

There are three cases here with slightly different behavior:

1) read_tempreg_nb_zen():
	This is a function pointer which does not include a return code.
	In this case, set the register value to 0 on failure. This
	enforces Read-as-Zero behavior.

2) k10temp_read_temp():
	This function does have return codes, so return the error code
	from the failed register read. Continued operation is not
	necessary, since there is no valid data from the register.
	Furthermore, if the register value was set to 0, then the
	following operation would underflow.

3) k10temp_get_ccd_support():
	This function reads the same register from multiple CCD
	instances in a loop. And a bitmask is formed if a specific bit
	is set in each register instance. The loop should continue on a
	failed register read, skipping the bit check.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240606-fix-smn-bad-read-v4-3-ffde21931c3f@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Yazen Ghannam 2024-06-06 11:12:56 -05:00 • committed by Greg Kroah-Hartman

parent a3480e59fd

commit 1bec77826f

1 changed files with 27 additions and 9 deletions

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drivers/hwmon/k10temp.c

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