linux-kernel - Re: [PATCH] crypto: ccp - Always pass in an error pointer to __sev_platform_shutdown

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Message-ID: <8f7eec03-3d9d-49ff-9457-f966ed2fc424@amd.com>
Date: Sat, 6 Sep 2025 16:15:15 -0500
From: "Kalra, Ashish" <ashish.kalra@....com>
To: Borislav Petkov <bp@...nel.org>
Cc: Tom Lendacky <thomas.lendacky@....com>,
 Herbert Xu <herbert@...dor.apana.org.au>, linux-crypto@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>, "Borislav Petkov (AMD)" <bp@...en8.de>,
 stable@...nel.org
Subject: Re: [PATCH] crypto: ccp - Always pass in an error pointer to
 __sev_platform_shutdown_locked()


On 9/6/2025 7:21 AM, Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@...en8.de>
> 
> When
> 
>   9770b428b1a2 ("crypto: ccp - Move dev_info/err messages for SEV/SNP init and shutdown")
> 
> moved the error messages dumping so that they don't need to be issued by
> the callers, it missed the case where __sev_firmware_shutdown() calls
> __sev_platform_shutdown_locked() with a NULL argument which leads to
> a NULL ptr deref on the shutdown path, during suspend to disk:
> 
>   #PF: supervisor read access in kernel mode
>   #PF: error_code(0x0000) - not-present page
>   PGD 0 P4D 0
>   Oops: Oops: 0000 [#1] SMP NOPTI
>   CPU: 0 UID: 0 PID: 983 Comm: hib.sh Not tainted 6.17.0-rc4+ #1 PREEMPT(voluntary)
>   Hardware name: Supermicro Super Server/H12SSL-i, BIOS 2.5 09/08/2022
>   RIP: 0010:__sev_platform_shutdown_locked.cold+0x0/0x21 [ccp]
> 
> That rIP is:
> 
>   00000000000006fd <__sev_platform_shutdown_locked.cold>:
>    6fd:   8b 13                   mov    (%rbx),%edx
>    6ff:   48 8b 7d 00             mov    0x0(%rbp),%rdi
>    703:   89 c1                   mov    %eax,%ecx
> 
>   Code: 74 05 31 ff 41 89 3f 49 8b 3e 89 ea 48 c7 c6 a0 8e 54 a0 41 bf 92 ff ff ff e8 e5 2e 09 e1 c6 05 2a d4 38 00 01 e9 26 af ff ff <8b> 13 48 8b 7d 00 89 c1 48 c7 c6 18 90 54 a0 89 44 24 04 e8 c1 2e
>   RSP: 0018:ffffc90005467d00 EFLAGS: 00010282
>   RAX: 00000000ffffff92 RBX: 0000000000000000 RCX: 0000000000000000
>   			     ^^^^^^^^^^^^^^^^
> and %rbx is nice and clean.
> 
>   Call Trace:
>    <TASK>
>    __sev_firmware_shutdown.isra.0
>    sev_dev_destroy
>    psp_dev_destroy
>    sp_destroy
>    pci_device_shutdown
>    device_shutdown
>    kernel_power_off
>    hibernate.cold
>    state_store
>    kernfs_fop_write_iter
>    vfs_write
>    ksys_write
>    do_syscall_64
>    entry_SYSCALL_64_after_hwframe
> 
> Pass in a pointer to the function-local error var in the caller.
> 
> With that addressed, suspending the ccp shows the error properly at
> least:
> 
>   ccp 0000:47:00.1: sev command 0x2 timed out, disabling PSP
>   ccp 0000:47:00.1: SEV: failed to SHUTDOWN error 0x0, rc -110
>   SEV-SNP: Leaking PFN range 0x146800-0x146a00
>   SEV-SNP: PFN 0x146800 unassigned, dumping non-zero entries in 2M PFN region: [0x146800 - 0x146a00]
>   ...
>   ccp 0000:47:00.1: SEV-SNP firmware shutdown failed, rc -16, error 0x0
>   ACPI: PM: Preparing to enter system sleep state S5
>   kvm: exiting hardware virtualization
>   reboot: Power down
> 
> Btw, this driver is crying to be cleaned up to pass in a proper I/O
> struct which can be used to store information between the different
> functions, otherwise stuff like that will happen in the future again.
> 
> Fixes: 9770b428b1a2 ("crypto: ccp - Move dev_info/err messages for SEV/SNP init and shutdown")
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
> Cc: <stable@...nel.org>
> ---
>  drivers/crypto/ccp/sev-dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index e058ba027792..9f5ccc1720cb 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -2430,7 +2430,7 @@ static void __sev_firmware_shutdown(struct sev_device *sev, bool panic)
>  {
>  	int error;
>  
> -	__sev_platform_shutdown_locked(NULL);
> +	__sev_platform_shutdown_locked(&error);
>  
>  	if (sev_es_tmr) {
>  		/*

Reviewed-by: Ashish Kalra <ashish.kalra@....com>

Thanks,
Ashish