diff mbox series

[net-next] tcp: fix signed/unsigned comparison

Message ID 20220417171027.3888810-1-eric.dumazet@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next] tcp: fix signed/unsigned comparison | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/cc_maintainers warning 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 3 this patch: 3
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

Eric Dumazet April 17, 2022, 5:10 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

Kernel test robot reported:

smatch warnings:
net/ipv4/tcp_input.c:5966 tcp_rcv_established() warn: unsigned 'reason' is never less than zero.

I actually had one packetdrill failing because of this bug,
and was about to send the fix :)

Fixes: 4b506af9c5b8 ("tcp: add two drop reasons for tcp_ack()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: kernel test robot <lkp@intel.com>
---
 net/ipv4/tcp_input.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andreas Schwab April 17, 2022, 6:24 p.m. UTC | #1 
On Apr 17 2022, Eric Dumazet wrote:

> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index cf2dc19bb8c766c1d33406053fd61c0873f15489..0d88984e071531fb727bdee178b0c01fd087fe5f 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -5959,7 +5959,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
>  
>  step5:
>  	reason = tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT);
> -	if (reason < 0)
> +	if ((int)reason < 0)
>  		goto discard;
>  
>  	tcp_rcv_rtt_measure_ts(sk, skb);

Shouldn't reason be negated before passing it to tcp_drop_reason?
Eric Dumazet April 17, 2022, 6:28 p.m. UTC | #2 
On Sun, Apr 17, 2022 at 11:24 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Apr 17 2022, Eric Dumazet wrote:
>
> > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> > index cf2dc19bb8c766c1d33406053fd61c0873f15489..0d88984e071531fb727bdee178b0c01fd087fe5f 100644
> > --- a/net/ipv4/tcp_input.c
> > +++ b/net/ipv4/tcp_input.c
> > @@ -5959,7 +5959,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
> >
> >  step5:
> >       reason = tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT);
> > -     if (reason < 0)
> > +     if ((int)reason < 0)
> >               goto discard;
> >
> >       tcp_rcv_rtt_measure_ts(sk, skb);
>
> Shouldn't reason be negated before passing it to tcp_drop_reason?

Good catch, thanks !
diff mbox series

Patch

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index cf2dc19bb8c766c1d33406053fd61c0873f15489..0d88984e071531fb727bdee178b0c01fd087fe5f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5959,7 +5959,7 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 
 step5:
 	reason = tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT);
-	if (reason < 0)
+	if ((int)reason < 0)
 		goto discard;
 
 	tcp_rcv_rtt_measure_ts(sk, skb);