[PATCH 1/1] lib: fix access to hfeatures->extensions

[Xiang W]

在 2023-11-11星期六的 04:26 +0100，Heinrich Schuchardt写道：
> We may in future have more than xlen ISA extensions supported by OpenSBI.
> Commit 6259b2ec2d09 ("lib: utils/fdt: Fix fdt_parse_isa_extensions()
> implementation") therefore assumes that hfeatures->extensions is an array.
> We have to make this change in the rest of the code too.
> 
> Fixes: 6259b2ec2d09 ("lib: utils/fdt: Fix fdt_parse_isa_extensions() implementation")
> Addresses-Coverity-ID: 1568357 Out-of-bounds access
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
Similar to this:
https://lists.infradead.org/pipermail/opensbi/2023-October/005787.html

Regards,
Xiang W

> ---
>  include/sbi/sbi_hart.h      |  3 ++-
>  lib/sbi/sbi_hart.c          | 46 ++++++++++++++++++++-----------------
>  platform/generic/platform.c |  2 +-
>  3 files changed, 28 insertions(+), 23 deletions(-)
> 
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index e60f415..9a5335a 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -10,6 +10,7 @@
>  #ifndef __SBI_HART_H__
>  #define __SBI_HART_H__
>  
> +#include <sbi/sbi_bitops.h>
>  #include <sbi/sbi_types.h>
>  
>  /** Possible privileged specification versions of a hart */
> @@ -65,7 +66,7 @@ enum sbi_hart_extensions {
>  struct sbi_hart_features {
>  	bool detected;
>  	int priv_version;
> -	unsigned long extensions;
> +	unsigned long extensions[BITS_TO_LONGS(SBI_HART_EXT_MAX)];
>  	unsigned int pmp_count;
>  	unsigned int pmp_addr_bits;
>  	unsigned long pmp_gran;
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index 29d6481..c3fccb3 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -614,9 +614,9 @@ static inline void __sbi_hart_update_extension(
>  					bool enable)
>  {
>  	if (enable)
> -		hfeatures->extensions |= BIT(ext);
> +		hfeatures->extensions[BIT_WORD(ext)] |= BIT_MASK(ext);
>  	else
> -		hfeatures->extensions &= ~BIT(ext);
> +		hfeatures->extensions[BIT_WORD(ext)] &= ~BIT_MASK(ext);
>  }
>  
>  /**
> @@ -649,7 +649,7 @@ bool sbi_hart_has_extension(struct sbi_scratch *scratch,
>  	struct sbi_hart_features *hfeatures =
>  			sbi_scratch_offset_ptr(scratch, hart_features_offset);
>  
> -	if (hfeatures->extensions & BIT(ext))
> +	if (hfeatures->extensions[BIT_WORD(ext)] & BIT_MASK(ext))
>  		return true;
>  	else
>  		return false;
> @@ -705,31 +705,35 @@ void sbi_hart_get_extensions_str(struct sbi_scratch *scratch,
>  {
>  	struct sbi_hart_features *hfeatures =
>  			sbi_scratch_offset_ptr(scratch, hart_features_offset);
> -	int offset = 0, ext = 0;
> -	char *temp;
> +	int offset = 0;
>  
>  	if (!extensions_str || nestr <= 0)
>  		return;
>  	sbi_memset(extensions_str, 0, nestr);
>  
> -	if (!hfeatures->extensions)
> -		goto done;
> -
> -	do {
> -		if (hfeatures->extensions & BIT(ext)) {
> -			temp = sbi_hart_extension_id2string(ext);
> -			if (temp) {
> -				sbi_snprintf(extensions_str + offset,
> -					     nestr - offset,
> -					     "%s,", temp);
> -				offset = offset + sbi_strlen(temp) + 1;
> +	for (int word = 0; word < BITS_TO_LONGS(SBI_HART_EXT_MAX); ++word) {
> +		int ext;
> +
> +		if (!hfeatures->extensions[word])
> +			continue;
> +
> +		ext = word * BITS_PER_LONG;
> +		for (int bit = 0; bit < BITS_PER_LONG && ext < SBI_HART_EXT_MAX;
> +		     ++bit, ++ext) {
> +			char *temp;
> +
> +			if (hfeatures->extensions[word] & BIT(bit)) {
> +				temp = sbi_hart_extension_id2string(ext);
> +				if (temp) {
> +					sbi_snprintf(extensions_str + offset,
> +						     nestr - offset,
> +						     "%s,", temp);
> +					offset += sbi_strlen(temp) + 1;
> +				}
>  			}
>  		}
> +	}
>  
> -		ext++;
> -	} while (ext < SBI_HART_EXT_MAX);
> -
> -done:
>  	if (offset)
>  		extensions_str[offset - 1] = '\0';
>  	else
> @@ -799,7 +803,7 @@ static int hart_detect_features(struct sbi_scratch *scratch)
>  		return 0;
>  
>  	/* Clear hart features */
> -	hfeatures->extensions = 0;
> +	sbi_memset(hfeatures->extensions, 0, sizeof(hfeatures->extensions));
>  	hfeatures->pmp_count = 0;
>  	hfeatures->mhpm_mask = 0;
>  
> diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> index 66a0b77..9182faa 100644
> --- a/platform/generic/platform.c
> +++ b/platform/generic/platform.c
> @@ -215,7 +215,7 @@ static int generic_extensions_init(struct sbi_hart_features *hfeatures)
>  
>  	/* Parse the ISA string from FDT and enable the listed extensions */
>  	rc = fdt_parse_isa_extensions(fdt_get_address(), current_hartid(),
> -				      &hfeatures->extensions);
> +				      hfeatures->extensions);
>  
>  	if (rc)
>  		return rc;
> -- 
> 2.40.1
> 
>