diff mbox series

[2/2] Ensure num_actions is not a negative

Message ID 20230901010437.126631-3-joao@overdrivepizza.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series Prevent potential write out of bounds | expand

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Context Check Description
netdev/series_format warning Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1331 this patch: 1331
netdev/cc_maintainers success CCed 10 of 10 maintainers
netdev/build_clang success Errors and warnings before: 1353 this patch: 1353
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1354 this patch: 1354
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Joao Moreira Sept. 1, 2023, 1:04 a.m. UTC 
From: Joao Moreira <joao.moreira@intel.com>

In nft_flow_rule_create function, num_actions is a signed integer. Yet,
it is processed within a loop which increments its value. To prevent an
overflow from occurring, check if num_actions is not only equal to 0,
but also not negative.

After checking with maintainers, it was mentioned that front-end will
cap the num_actions vlaue and that it is not possible to reach such
condition for an overflow. Yet, for correctness, it is still better to
fix this.

Signed-off-by: Joao Moreira <joao.moreira@intel.com>
---
 net/netfilter/nf_tables_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Pablo Neira Ayuso Sept. 1, 2023, 8:58 a.m. UTC | #1 
On Thu, Aug 31, 2023 at 06:04:37PM -0700, joao@overdrivepizza.com wrote:
> From: Joao Moreira <joao.moreira@intel.com>
> 
> In nft_flow_rule_create function, num_actions is a signed integer. Yet,
> it is processed within a loop which increments its value. To prevent an
> overflow from occurring, check if num_actions is not only equal to 0,
> but also not negative.
> 
> After checking with maintainers, it was mentioned that front-end will
> cap the num_actions vlaue and that it is not possible to reach such
> condition for an overflow. Yet, for correctness, it is still better to
> fix this.
> 
> Signed-off-by: Joao Moreira <joao.moreira@intel.com>
> ---
>  net/netfilter/nf_tables_offload.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
> index 12ab78fa5d84..20dbc95de895 100644
> --- a/net/netfilter/nf_tables_offload.c
> +++ b/net/netfilter/nf_tables_offload.c
> @@ -102,7 +102,7 @@ struct nft_flow_rule *nft_flow_rule_create(struct net *net,
>  		expr = nft_expr_next(expr);
>  	}
>  
> -	if (num_actions == 0)
> +	if (num_actions <= 0)
>  		return ERR_PTR(-EOPNOTSUPP);

Better turn num_actions into unsigned int I'd suggest.

Next hypothetical problem would be an overflow in the number of
actions, you could check for UINT_MAX if you like here to report
ENOMEM.

Thanks.

>  	flow = nft_flow_rule_alloc(num_actions);
> -- 
> 2.41.0
>
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 12ab78fa5d84..20dbc95de895 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -102,7 +102,7 @@  struct nft_flow_rule *nft_flow_rule_create(struct net *net,
 		expr = nft_expr_next(expr);
 	}
 
-	if (num_actions == 0)
+	if (num_actions <= 0)
 		return ERR_PTR(-EOPNOTSUPP);
 
 	flow = nft_flow_rule_alloc(num_actions);