Commit 028c6f11 authored by Yazen Ghannam's avatar Yazen Ghannam Committed by Wei Li
Browse files

x86/amd_nb: Check for invalid SMN reads 

stable inclusion
from stable-v4.19.317
commit d4e52b36c73f44d2b5f41d0cd3f57b3d2efbf180
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAMTH9
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d4e52b36c73f44d2b5f41d0cd3f57b3d2efbf180



--------------------------------

[ Upstream commit c625dabbf1c4a8e77e4734014f2fde7aa9071a1f ]

AMD Zen-based systems use a System Management Network (SMN) that
provides access to implementation-specific registers.

SMN accesses are done indirectly through an index/data pair in PCI
config space. The PCI config access may fail and return an error code.
This would prevent the "read" value from being updated.

However, the PCI config access may succeed, but the return value may be
invalid. This is in similar fashion to PCI bad reads, i.e. return all
bits set.

Most systems will return 0 for SMN addresses that are not accessible.
This is in line with AMD convention that unavailable registers are
Read-as-Zero/Writes-Ignored.

However, some systems will return a "PCI Error Response" instead. This
value, along with an error code of 0 from the PCI config access, will
confuse callers of the amd_smn_read() function.

Check for this condition, clear the return value, and set a proper error
code.

Fixes: ddfe43cd ("x86/amd_nb: Add SMN and Indirect Data Fabric access for AMD Fam17h")
Signed-off-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230403164244.471141-1-yazen.ghannam@amd.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarWei Li <liwei391@huawei.com>
parent 332daec1

arch/x86/kernel/amd_nb.c

+8 −1
Original line number Diff line number Diff line
@@ -173,7 +173,14 @@ static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write) 


int amd_smn_read(u16 node, u32 address, u32 *value)

{

	return __amd_smn_rw(node, address, value, false);

	int err = __amd_smn_rw(node, address, value, false);



	if (PCI_POSSIBLE_ERROR(*value)) {

		err = -ENODEV;

		*value = 0;

	}



	return err;

}

EXPORT_SYMBOL_GPL(amd_smn_read);