[PATCH v2 3/6] lib: sbi_dbtr: use range check for shared memory domain validation

[Himanshu Chauhan]

On Fri, Jul 31, 2026 at 10:34:02AM +0000, liutong wrote:
> sbi_dbtr_setup_shmem() validates the shared memory address using
> sbi_domain_check_addr(), which only checks a single address. However,
> subsequent DBTR operations (install, read, update) access up to
> total_trigs * sizeof(sbi_dbtr_shmem_entry) bytes starting from that
> address.
> 
> If the shared memory region spans a domain boundary, accesses beyond
> the first byte could violate domain isolation, allowing S-mode to
> read or write M-mode memory through DBTR operations.
> 
> Replace the single-address check with sbi_domain_check_addr_range()
> to validate the entire shared memory region that DBTR operations
> will use.
> 
> Fixes: 23b7badeee3c ("lib: sbi: check incoming dbtr shmem address")
> Signed-off-by: liutong <liutong at iscas.ac.cn>
> ---
> 
> Previously sent as [PATCH v2].
> Changes in v2:
> - Added Fixes tag
> - Consolidated into patch series
> 
>  lib/sbi/sbi_dbtr.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/sbi/sbi_dbtr.c b/lib/sbi/sbi_dbtr.c
> index 5cca0922..b0f1019d 100644
> --- a/lib/sbi/sbi_dbtr.c
> +++ b/lib/sbi/sbi_dbtr.c
> @@ -304,9 +304,10 @@ int sbi_dbtr_setup_shmem(const struct sbi_domain *dom, unsigned long smode,
>  	if (shmem_phys_hi)
>  		return SBI_EINVALID_ADDR;
>  
> -	if (dom && !sbi_domain_check_addr(dom,
> -		  DBTR_SHMEM_MAKE_PHYS(shmem_phys_hi, shmem_phys_lo), smode,
> -		  SBI_DOMAIN_READ | SBI_DOMAIN_WRITE))
> +	if (dom && !sbi_domain_check_addr_range(dom,
> +		  DBTR_SHMEM_MAKE_PHYS(shmem_phys_hi, shmem_phys_lo),
> +		  hart_state->total_trigs * sizeof(union sbi_dbtr_shmem_entry),
> +		  smode, SBI_DOMAIN_READ | SBI_DOMAIN_WRITE))
>  		return SBI_ERR_INVALID_ADDRESS;
>
one nit pick: The dom && guard means the range check is skipped entirely if dom is NULL. Since you are
trying to close gaps, I would suggest that you add a check for dom.

Regards
Himanshu
  
>  	hart_state->shmem.phys_lo = shmem_phys_lo;
> -- 
> 2.34.1
> 
> 
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