Brijesh Singh [off-list ref] wrote:

Paulian reported the below kernel crash on Ryzen 5 system:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000073
RIP: 0010:.LC0+0x41f/0xa00
RSP: 0018:ffffa9968003bdd0 EFLAGS: 00010002
RAX: ffffffffb113b130 RBX: 0000000000000000 RCX: 00000000000005a7
RDX: 00000000000000ff RSI: ffff8b46dee651a0 RDI: ffffffffb1bd617c
RBP: 0000000000000246 R08: 00000000000251a0 R09: 0000000000000000
R10: ffffd81f11a38200 R11: ffff8b52e8e0a161 R12: ffffffffb19db220
R13: 0000000000000007 R14: ffffffffb17e4888 R15: 5dccd7affc30a31e
FS:  0000000000000000(0000) GS:ffff8b46dee40000(0000) knlGS:0000000000000000
CR2: 0000000000000073 CR3: 000080128120a000 CR4: 00000000003406e0
Call Trace:
? sp_get_psp_master_device+0x56/0x80
? map_properties+0x540/0x540
? psp_pci_init+0x20/0xe0
? map_properties+0x540/0x540
? sp_mod_init+0x16/0x1a
? do_one_initcall+0x4b/0x190
? kernel_init_freeable+0x19b/0x23c
? rest_init+0xb0/0xb0
? kernel_init+0xa/0x100
? ret_from_fork+0x22/0x40

Since Ryzen does not support PSP/SEV firmware hence i->psp_data will
NULL in all sp instances. In those cases, 'i' will point to the
list head after list_for_each_entry(). Dereferencing the head will
cause kernel crash.

Add check to call get master device only when PSP/SEV is detected.

Reported-by: Paulian Bogdan Marinca <redacted>
Cc: Borislav Petkov <redacted>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
CC: Gary R Hook <redacted>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <redacted>
---

Changes since v1:

v1 contained a local change I used for triggering the crash on EPYC system.
we do not need those changes in final patch.

Patch applied.  Thanks.
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt