diff mbox series

[v2,net-next,1/2] tcp: fix over estimation in sk_forced_mem_schedule()

Message ID 20220614171734.1103875-2-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series tcp: final (?) round of mem pressure fixes | 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 Series has a cover letter
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: 2 this patch: 2
netdev/cc_maintainers warning 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 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 June 14, 2022, 5:17 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

sk_forced_mem_schedule() has a bug similar to ones fixed
in commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
sk_rmem_schedule() errors")

While this bug has little chance to trigger in old kernels,
we need to fix it before the following patch.

Fixes: d83769a580f1 ("tcp: fix possible deadlock in tcp_send_fin()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_output.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Soheil Hassas Yeganeh June 14, 2022, 5:40 p.m. UTC | #1 
On Tue, Jun 14, 2022 at 1:17 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> sk_forced_mem_schedule() has a bug similar to ones fixed
> in commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
> sk_rmem_schedule() errors")
>
> While this bug has little chance to trigger in old kernels,
> we need to fix it before the following patch.
>
> Fixes: d83769a580f1 ("tcp: fix possible deadlock in tcp_send_fin()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Soheil Hassas Yeganeh <soheil@google.com>

> ---
>  net/ipv4/tcp_output.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 8ab98e1aca6797a51eaaf8886680d2001a616948..18c913a2347a984ae8cf2793bb8991e59e5e94ab 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3362,11 +3362,12 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
>   */
>  void sk_forced_mem_schedule(struct sock *sk, int size)
>  {
> -       int amt;
> +       int delta, amt;
>
> -       if (size <= sk->sk_forward_alloc)
> +       delta = size - sk->sk_forward_alloc;
> +       if (delta <= 0)
>                 return;
> -       amt = sk_mem_pages(size);
> +       amt = sk_mem_pages(delta);
>         sk->sk_forward_alloc += amt << PAGE_SHIFT;
>         sk_memory_allocated_add(sk, amt);
>
> --
> 2.36.1.476.g0c4daa206d-goog
>
Shakeel Butt June 14, 2022, 5:40 p.m. UTC | #2 
On Tue, Jun 14, 2022 at 10:17:33AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> sk_forced_mem_schedule() has a bug similar to ones fixed
> in commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
> sk_rmem_schedule() errors")
> 
> While this bug has little chance to trigger in old kernels,
> we need to fix it before the following patch.
> 
> Fixes: d83769a580f1 ("tcp: fix possible deadlock in tcp_send_fin()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>
Wei Wang June 14, 2022, 6:39 p.m. UTC | #3 
On Tue, Jun 14, 2022 at 10:41 AM Soheil Hassas Yeganeh
<soheil@google.com> wrote:
>
> On Tue, Jun 14, 2022 at 1:17 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >
> > From: Eric Dumazet <edumazet@google.com>
> >
> > sk_forced_mem_schedule() has a bug similar to ones fixed
> > in commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
> > sk_rmem_schedule() errors")
> >
> > While this bug has little chance to trigger in old kernels,
> > we need to fix it before the following patch.
> >
> > Fixes: d83769a580f1 ("tcp: fix possible deadlock in tcp_send_fin()")
> > Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Wei Wang <weiwan@google.com>

>
> Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
>
> > ---
> >  net/ipv4/tcp_output.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> > index 8ab98e1aca6797a51eaaf8886680d2001a616948..18c913a2347a984ae8cf2793bb8991e59e5e94ab 100644
> > --- a/net/ipv4/tcp_output.c
> > +++ b/net/ipv4/tcp_output.c
> > @@ -3362,11 +3362,12 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
> >   */
> >  void sk_forced_mem_schedule(struct sock *sk, int size)
> >  {
> > -       int amt;
> > +       int delta, amt;
> >
> > -       if (size <= sk->sk_forward_alloc)
> > +       delta = size - sk->sk_forward_alloc;
> > +       if (delta <= 0)
> >                 return;
> > -       amt = sk_mem_pages(size);
> > +       amt = sk_mem_pages(delta);
> >         sk->sk_forward_alloc += amt << PAGE_SHIFT;
> >         sk_memory_allocated_add(sk, amt);
> >
> > --
> > 2.36.1.476.g0c4daa206d-goog
> >
diff mbox series

Patch

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8ab98e1aca6797a51eaaf8886680d2001a616948..18c913a2347a984ae8cf2793bb8991e59e5e94ab 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3362,11 +3362,12 @@  void tcp_xmit_retransmit_queue(struct sock *sk)
  */
 void sk_forced_mem_schedule(struct sock *sk, int size)
 {
-	int amt;
+	int delta, amt;
 
-	if (size <= sk->sk_forward_alloc)
+	delta = size - sk->sk_forward_alloc;
+	if (delta <= 0)
 		return;
-	amt = sk_mem_pages(size);
+	amt = sk_mem_pages(delta);
 	sk->sk_forward_alloc += amt << PAGE_SHIFT;
 	sk_memory_allocated_add(sk, amt);