[PATCH 0/2] Fix bug #80 again

[PATCH 0/2] Fix bug #80 again

[Stefano Brivio]

Oops.

Stefano Brivio (2):
  Revert "udp: Make rport calculation more local"
  udp: Reduce scope of rport in udp_invert_portmap()

 udp.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

-- 
2.43.0

[PATCH 1/2] Revert "udp: Make rport calculation more local"

[Stefano Brivio]

This reverts commit c80fa6a6bb4415ad48f9e11424310875d0d99bc7, as it
reintroduces the issue fixed by commit 1e6f92b995a9 ("udp: Fix 16-bit
overflow in udp_invert_portmap()").

Reported-by: Laurent Jacquot <jk@lutty.net>
Link: https://bugs.passt.top/show_bug.cgi?id=80
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 udp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/udp.c b/udp.c
index e79ca93..8181900 100644
--- a/udp.c
+++ b/udp.c
@@ -279,9 +279,10 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
 		      "Forward and reverse delta arrays must have same size");
 	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
 		in_port_t delta = fwd->f.delta[i];
+		in_port_t rport = i + delta;
 
 		if (delta)
-			fwd->rdelta[i + delta] = NUM_PORTS - delta;
+			fwd->rdelta[rport] = NUM_PORTS - delta;
 	}
 }
 
-- 
@@ -279,9 +279,10 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
 		      "Forward and reverse delta arrays must have same size");
 	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
 		in_port_t delta = fwd->f.delta[i];
+		in_port_t rport = i + delta;
 
 		if (delta)
-			fwd->rdelta[i + delta] = NUM_PORTS - delta;
+			fwd->rdelta[rport] = NUM_PORTS - delta;
 	}
 }
 
-- 
2.43.0

[PATCH 2/2] udp: Reduce scope of rport in udp_invert_portmap()

[Stefano Brivio]

cppcheck 2.14 warns that the scope of the rport variable could be
reduced: do that, as reverted commit c80fa6a6bb44 ("udp: Make rport
calculation more local") did, but keep the temporary variable of
in_port_t type, otherwise the sum gets promoted to int.

Reported-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 udp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/udp.c b/udp.c
index 8181900..a854323 100644
--- a/udp.c
+++ b/udp.c
@@ -279,10 +279,12 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
 		      "Forward and reverse delta arrays must have same size");
 	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
 		in_port_t delta = fwd->f.delta[i];
-		in_port_t rport = i + delta;
 
-		if (delta)
+		if (delta) {
+			in_port_t rport = i + delta;
+
 			fwd->rdelta[rport] = NUM_PORTS - delta;
+		}
 	}
 }
 
-- 
@@ -279,10 +279,12 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
 		      "Forward and reverse delta arrays must have same size");
 	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
 		in_port_t delta = fwd->f.delta[i];
-		in_port_t rport = i + delta;
 
-		if (delta)
+		if (delta) {
+			in_port_t rport = i + delta;
+
 			fwd->rdelta[rport] = NUM_PORTS - delta;
+		}
 	}
 }
 
-- 
2.43.0

Re: [PATCH 1/2] Revert "udp: Make rport calculation more local"

[David Gibson]

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On Fri, Jun 21, 2024 at 05:53:22PM +0200, Stefano Brivio wrote:
> This reverts commit c80fa6a6bb4415ad48f9e11424310875d0d99bc7, as it
> reintroduces the issue fixed by commit 1e6f92b995a9 ("udp: Fix 16-bit
> overflow in udp_invert_portmap()").
> 
> Reported-by: Laurent Jacquot <jk@lutty.net>
> Link: https://bugs.passt.top/show_bug.cgi?id=80
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Argh, dammit.  So,

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

.. but I think we really need to put a comment on this, otherwise one
of us is likely to make the same mistake again, because that
particular promotion rule is truly arcane.

> ---
>  udp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/udp.c b/udp.c
> index e79ca93..8181900 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -279,9 +279,10 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
>  		      "Forward and reverse delta arrays must have same size");
>  	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
>  		in_port_t delta = fwd->f.delta[i];
> +		in_port_t rport = i + delta;
>  
>  		if (delta)
> -			fwd->rdelta[i + delta] = NUM_PORTS - delta;
> +			fwd->rdelta[rport] = NUM_PORTS - delta;
>  	}
>  }
>  

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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Re: [PATCH 2/2] udp: Reduce scope of rport in udp_invert_portmap()

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 1322 bytes --]

On Fri, Jun 21, 2024 at 05:53:23PM +0200, Stefano Brivio wrote:
> cppcheck 2.14 warns that the scope of the rport variable could be
> reduced: do that, as reverted commit c80fa6a6bb44 ("udp: Make rport
> calculation more local") did, but keep the temporary variable of
> in_port_t type, otherwise the sum gets promoted to int.
> 
> Reported-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  udp.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/udp.c b/udp.c
> index 8181900..a854323 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -279,10 +279,12 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
>  		      "Forward and reverse delta arrays must have same size");
>  	for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
>  		in_port_t delta = fwd->f.delta[i];
> -		in_port_t rport = i + delta;
>  
> -		if (delta)
> +		if (delta) {
> +			in_port_t rport = i + delta;
> +
>  			fwd->rdelta[rport] = NUM_PORTS - delta;
> +		}
>  	}
>  }
>  

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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Re: [PATCH 1/2] Revert "udp: Make rport calculation more local"

[Stefano Brivio]

On Mon, 24 Jun 2024 11:20:48 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Fri, Jun 21, 2024 at 05:53:22PM +0200, Stefano Brivio wrote:
> > This reverts commit c80fa6a6bb4415ad48f9e11424310875d0d99bc7, as it
> > reintroduces the issue fixed by commit 1e6f92b995a9 ("udp: Fix 16-bit
> > overflow in udp_invert_portmap()").
> > 
> > Reported-by: Laurent Jacquot <jk@lutty.net>
> > Link: https://bugs.passt.top/show_bug.cgi?id=80
> > Signed-off-by: Stefano Brivio <sbrivio@redhat.com>  
> 
> Argh, dammit.  So,
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> 
> .. but I think we really need to put a comment on this, otherwise one
> of us is likely to make the same mistake again, because that
> particular promotion rule is truly arcane.

Pushed with a comment (part of commit for 2/2), I hope it's clear
enough now.

-- 
Stefano