From: Al Viro <viro@zeniv.linux.org.uk>
To: gus Gusenleitner Klaus <gus@keba.com>
Cc: Al Viro <viro@ftp.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, "bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"dsahern@kernel.org" <dsahern@kernel.org>,
"edumazet@google.com" <edumazet@google.com>,
"kuba@kernel.org" <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Subject: Re: AW: [PATCH] amd64: Fix csum_partial_copy_generic()
Date: Thu, 19 Oct 2023 07:14:27 +0100 [thread overview]
Message-ID: <20231019061427.GW800259@ZenIV> (raw)
In-Reply-To: <20231019050250.GV800259@ZenIV>
On Thu, Oct 19, 2023 at 06:02:50AM +0100, Al Viro wrote:
> On Thu, Oct 19, 2023 at 04:44:04AM +0000, gus Gusenleitner Klaus wrote:
> > > On Wed, Oct 18, 2023 at 06:18:05AM +0000, gus Gusenleitner Klaus wrote:
> > > > The checksum calculation is wrong in case of an source buffer
> > > > containing zero bytes only. The expected return value is 0, the
> > > > actual return value is 0xfffffff.
> > >
> > > Expected where? The actual checksum is defined modulo 0xffff, so
> > > 0 and 0xffffffff represent the same final value.
> > >
> > > The only twist is that in some situations we internally use 0 for
> > > "not calculated yet".
> > >
> > > > This problem occurs when a ICMP echo reply is sent that has set
> > > > zero identifier, sequence number and data.
> > >
> > > What problem? Could you please either point to specific RFC or
> > > show that packets are rejected by some existing system, or...?
> >
> > Here's our situation:
> > Our device gets pinged by a third party manufacturer robot controller.
> > We have updated the kernel in our device to 5.15 from 4.9, the robot
> > controller is kept unchanged. At 4.9, our device's ping reply is accepted
> > by the robot controller, at 5.15 it's not.
> >
> > Wireshark shows a bad checksum warning:
> > 'Checksum: 0x0000 incorrect, should be 0xffff'
> >
>
> Lovely. I think I see what's going on, give me a few to think about it...
The real source of trouble was switching csum_and_copy_{to,from}_user()
to reporting faults as 0. And yes, it's broken. Bugger...
next prev parent reply other threads:[~2023-10-19 6:14 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-18 6:18 [PATCH] amd64: Fix csum_partial_copy_generic() gus Gusenleitner Klaus
2023-10-18 7:36 ` Eric Dumazet
2023-10-18 15:12 ` Thomas Gleixner
2023-10-18 15:42 ` Al Viro
2023-10-18 17:37 ` Thomas Gleixner
2023-10-19 4:44 ` AW: " gus Gusenleitner Klaus
2023-10-19 5:02 ` Al Viro
2023-10-19 6:14 ` Al Viro [this message]
2023-10-19 6:39 ` Al Viro
2023-10-19 7:39 ` Eric Dumazet
2023-10-19 8:06 ` Al Viro
2023-10-20 8:32 ` Vincent Whitchurch
2023-10-20 20:27 ` David Laight
2023-10-21 7:15 ` Al Viro
2023-10-21 22:22 ` Al Viro
2023-10-22 11:03 ` David Laight
2023-10-22 11:11 ` Al Viro
2023-10-23 8:16 ` David Laight
2023-10-24 2:59 ` Al Viro
2023-10-22 19:40 ` [RFC][PATCH] fix csum_and_copy_..._user() idiocy. " Al Viro
2023-10-22 19:46 ` Al Viro
2023-10-23 10:37 ` Thomas Gleixner
2023-10-24 4:26 ` Al Viro
2023-10-24 12:31 ` Thomas Gleixner
2023-10-23 14:44 ` David Laight
2023-10-24 3:53 ` Al Viro
2023-12-05 2:21 ` [RFC][PATCHES v2] checksum stuff Al Viro
2023-12-05 2:23 ` [PATCH v2 01/18] make net/checksum.h self-contained Al Viro
2023-12-05 2:23 ` [PATCH v2 1/9] reiserfs: Avoid touching renamed directory if parent does not change Al Viro
2023-12-05 2:23 ` [PATCH v2 02/18] get rid of asm/checksum.h includes outside of include/net/checksum.h and arch Al Viro
2023-12-05 2:23 ` [PATCH v2 2/9] ocfs2: Avoid touching renamed directory if parent does not change Al Viro
2023-12-05 2:23 ` [PATCH v2 03/18] make net/checksum.h the sole user of asm/checksum.h Al Viro
2023-12-05 2:23 ` [PATCH v2 3/9] udf_rename(): only access the child content on cross-directory rename Al Viro
2023-12-05 2:23 ` [PATCH v2 4/9] ext2: Avoid reading renamed directory if parent does not change Al Viro
2023-12-05 2:23 ` [PATCH v2 04/18] Fix the csum_and_copy_..._user() idiocy Al Viro
2023-12-05 2:24 ` [PATCH v2 05/18] bits missing from csum_and_copy_{from,to}_user() unexporting Al Viro
2023-12-05 2:24 ` [PATCH v2 5/9] ext4: don't access the source subdirectory content on same-directory rename Al Viro
2023-12-05 2:24 ` [PATCH v2 06/18] consolidate csum_tcpudp_magic(), take default variant into net/checksum.h Al Viro
2023-12-05 2:24 ` [PATCH v2 6/9] f2fs: Avoid reading renamed directory if parent does not change Al Viro
2023-12-05 2:24 ` [PATCH v2 07/18] consolidate default ip_compute_csum() Al Viro
2023-12-05 2:24 ` [PATCH v2 7/9] rename(): fix the locking of subdirectories Al Viro
2023-12-05 2:24 ` [PATCH v2 08/18] alpha: pull asm-generic/checksum.h Al Viro
2023-12-05 2:24 ` [PATCH v2 8/9] kill lock_two_inodes() Al Viro
2023-12-05 2:24 ` [PATCH v2 09/18] mips: pull include of asm-generic/checksum.h out of #if Al Viro
2023-12-05 2:24 ` [PATCH v2 9/9] rename(): avoid a deadlock in the case of parents having no common ancestor Al Viro
2023-12-05 2:24 ` [PATCH v2 10/18] nios2: pull asm-generic/checksum.h Al Viro
2023-12-05 2:24 ` [PATCH v2 11/18] x86: merge csum_fold() for 32bit and 64bit Al Viro
2023-12-05 2:24 ` [PATCH v2 12/18] x86: merge ip_fast_csum() " Al Viro
2023-12-05 2:24 ` [PATCH v2 13/18] x86: merge csum_tcpudp_nofold() " Al Viro
2023-12-05 2:24 ` [PATCH v2 14/18] amd64: saner handling of odd address in csum_partial() Al Viro
2023-12-05 2:24 ` [PATCH v2 15/18] x86: optimized csum_add() is the same for 32bit and 64bit Al Viro
2023-12-05 2:24 ` [PATCH v2 16/18] x86: lift the extern for csum_partial() into checksum.h Al Viro
2023-12-05 2:24 ` [PATCH v2 17/18] x86_64: move csum_ipv6_magic() from csum-wrappers_64.c to csum-partial_64.c Al Viro
2023-12-05 2:24 ` [PATCH v2 18/18] uml/x86: use normal x86 checksum.h Al Viro
2024-01-03 22:02 ` Richard Weinberger
2023-12-05 2:27 ` [RFC][PATCHES v2] checksum stuff Al Viro
2023-12-06 11:10 ` David Laight
2023-12-06 22:43 ` Al Viro
2023-12-07 9:58 ` David Laight
2023-12-08 12:04 ` David Laight
2023-12-08 14:17 ` Al Viro
2023-12-08 15:29 ` Al Viro
2023-12-08 15:56 ` David Laight
2023-12-08 18:35 ` Al Viro
2023-10-19 11:45 ` AW: [PATCH] amd64: Fix csum_partial_copy_generic() Thomas Gleixner
2023-10-19 10:33 ` David Laight
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