* [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition
@ 2022-03-12 16:27 Alexander Vorwerk
2022-03-12 17:19 ` Al Viro
2022-03-12 17:19 ` Stephen Hemminger
0 siblings, 2 replies; 3+ messages in thread
From: Alexander Vorwerk @ 2022-03-12 16:27 UTC (permalink / raw)
To: edumazet, davem, yoshfuji, dsahern, kuba
Cc: netdev, linux-kernel, Alexander Vorwerk
reported by checkpatch.pl
Signed-off-by: Alexander Vorwerk <alexander.vorwerk@stud.uni-goettingen.de>
---
net/ipv4/tcp.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 28ff2a820f7c..7fa6e7e6ea80 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -959,10 +959,10 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
struct sk_buff *skb = tcp_write_queue_tail(sk);
struct tcp_sock *tp = tcp_sk(sk);
bool can_coalesce;
- int copy, i;
+ int copy = size_goal - skb->len;
+ int i;
- if (!skb || (copy = size_goal - skb->len) <= 0 ||
- !tcp_skb_can_collapse_to(skb)) {
+ if (!skb || copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
new_segment:
if (!sk_stream_memory_free(sk))
return NULL;
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition
2022-03-12 16:27 [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition Alexander Vorwerk
@ 2022-03-12 17:19 ` Al Viro
2022-03-12 17:19 ` Stephen Hemminger
1 sibling, 0 replies; 3+ messages in thread
From: Al Viro @ 2022-03-12 17:19 UTC (permalink / raw)
To: Alexander Vorwerk
Cc: edumazet, davem, yoshfuji, dsahern, kuba, netdev, linux-kernel
On Sat, Mar 12, 2022 at 05:27:44PM +0100, Alexander Vorwerk wrote:
> reported by checkpatch.pl
... nicely demonstrating why checkpatch.pl is a menace.
> Signed-off-by: Alexander Vorwerk <alexander.vorwerk@stud.uni-goettingen.de>
> ---
> net/ipv4/tcp.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 28ff2a820f7c..7fa6e7e6ea80 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -959,10 +959,10 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
> struct sk_buff *skb = tcp_write_queue_tail(sk);
> struct tcp_sock *tp = tcp_sk(sk);
> bool can_coalesce;
> - int copy, i;
> + int copy = size_goal - skb->len;
> + int i;
>
> - if (!skb || (copy = size_goal - skb->len) <= 0 ||
> - !tcp_skb_can_collapse_to(skb)) {
> + if (!skb || copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
What is going to happen when you variant runs into
skb == NULL? And if for some reason that cannot happen, where
is the explanation of that reason?
IOW, this patch ends up quietly introducing a bug, with
no better rationale than "checkpatch.pl pointed me to that line".
NAKed-by: Al Viro <viro@zeniv.linux.org.uk>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition
2022-03-12 16:27 [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition Alexander Vorwerk
2022-03-12 17:19 ` Al Viro
@ 2022-03-12 17:19 ` Stephen Hemminger
1 sibling, 0 replies; 3+ messages in thread
From: Stephen Hemminger @ 2022-03-12 17:19 UTC (permalink / raw)
To: Alexander Vorwerk
Cc: edumazet, davem, yoshfuji, dsahern, kuba, netdev, linux-kernel
On Sat, 12 Mar 2022 17:27:44 +0100
Alexander Vorwerk <alexander.vorwerk@stud.uni-goettingen.de> wrote:
> reported by checkpatch.pl
>
> Signed-off-by: Alexander Vorwerk <alexander.vorwerk@stud.uni-goettingen.de>
> ---
> net/ipv4/tcp.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 28ff2a820f7c..7fa6e7e6ea80 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -959,10 +959,10 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
> struct sk_buff *skb = tcp_write_queue_tail(sk);
> struct tcp_sock *tp = tcp_sk(sk);
> bool can_coalesce;
> - int copy, i;
> + int copy = size_goal - skb->len;
> + int i;
>
> - if (!skb || (copy = size_goal - skb->len) <= 0 ||
> - !tcp_skb_can_collapse_to(skb)) {
> + if (!skb || copy <= 0 || !tcp_skb_can_collapse_to(skb)) {
> new_segment:
> if (!sk_stream_memory_free(sk))
> return NULL;
Your new code will crash if skb is NULL.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-03-12 16:27 [PATCH] net: ipv4: tcp.c: fix an assignment in an if condition Alexander Vorwerk
2022-03-12 17:19 ` Al Viro
2022-03-12 17:19 ` Stephen Hemminger
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