From: Al Viro <viro@zeniv•linux.org.uk>
To: Christoph Hellwig <hch@lst•de>
Cc: Arnd Bergmann <arnd@arndb•de>,
linux-kernel@vger•kernel.org, Jeremy Kerr <jk@ozlabs•org>,
linux-fsdevel@vger•kernel.org,
Andrew Morton <akpm@linux-foundation•org>,
linuxppc-dev@lists•ozlabs.org,
"Eric W . Biederman" <ebiederm@xmission•com>
Subject: Re: [PATCH 1/7] powerpc/spufs: simplify spufs core dumping
Date: Tue, 21 Apr 2020 20:25:36 +0100 [thread overview]
Message-ID: <20200421192536.GG23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200421191909.GF23230@ZenIV.linux.org.uk>
On Tue, Apr 21, 2020 at 08:19:09PM +0100, Al Viro wrote:
> On Tue, Apr 21, 2020 at 09:01:48PM +0200, Christoph Hellwig wrote:
> > On Tue, Apr 21, 2020 at 07:49:41PM +0100, Al Viro wrote:
> > > > spin_lock(&ctx->csa.register_lock);
> > > > - ret = __spufs_proxydma_info_read(ctx, buf, len, pos);
> > > > + __spufs_proxydma_info_read(ctx, &info);
> > > > + ret = simple_read_from_buffer(buf, len, pos, &info, sizeof(info));
> > >
> > > IDGI... What's that access_ok() for? If you are using simple_read_from_buffer(),
> > > the damn thing goes through copy_to_user(). Why bother with separate access_ok()
> > > here?
> >
> > I have no idea at all, this just refactors the code.
>
> Wait a bloody minute, it's doing *what* under a spinlock?
... and yes, I realize that it's been broken the same way. It still needs fixing.
AFAICS, that got broken in commit bf1ab978be23 "[POWERPC] coredump: Add SPU elf
notes to coredump." when spufs_proxydma_info_read() had copy_to_user() (until
then done after dropping the spinlock) moved into an area where blocking is very
much *not* allowed.
next prev parent reply other threads:[~2020-04-21 19:33 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 15:41 remove set_fs calls from the exec and coredump code v3 Christoph Hellwig
2020-04-21 15:41 ` [PATCH 1/7] powerpc/spufs: simplify spufs core dumping Christoph Hellwig
2020-04-21 18:49 ` Al Viro
2020-04-21 19:01 ` Christoph Hellwig
2020-04-21 19:19 ` Al Viro
2020-04-21 19:25 ` Al Viro [this message]
2020-04-21 15:41 ` [PATCH 2/7] signal: factor copy_siginfo_to_external32 from copy_siginfo_to_user32 Christoph Hellwig
2020-04-26 4:47 ` Andrew Morton
2020-04-26 7:40 ` Christoph Hellwig
2020-04-27 22:40 ` Andrew Morton
2020-04-28 7:09 ` Christoph Hellwig
2020-04-28 7:45 ` Christophe Leroy
2020-04-28 7:48 ` Christoph Hellwig
2020-04-28 19:56 ` [PATCH] fixup! " Arnd Bergmann
2020-04-29 6:17 ` Christophe Leroy
2020-04-29 6:29 ` Christoph Hellwig
2020-04-29 6:44 ` Christoph Hellwig
2020-04-29 8:07 ` Arnd Bergmann
2020-04-29 9:42 ` Christoph Hellwig
2020-04-29 11:28 ` Arnd Bergmann
2020-04-29 11:53 ` Christoph Hellwig
2020-04-29 12:34 ` Arnd Bergmann
2020-04-21 15:42 ` [PATCH 3/7] binfmt_elf: femove the set_fs in fill_siginfo_note Christoph Hellwig
2020-04-21 15:42 ` [PATCH 4/7] binfmt_elf: remove the set_fs(KERNEL_DS) in elf_core_dump Christoph Hellwig
2020-04-21 15:42 ` [PATCH 5/7] binfmt_elf_fdpic: remove the set_fs(KERNEL_DS) in elf_fdpic_core_dump Christoph Hellwig
2020-04-21 15:42 ` [PATCH 6/7] exec: simplify the copy_strings_kernel calling convention Christoph Hellwig
2020-04-21 15:42 ` [PATCH 7/7] exec: open code copy_string_kernel Christoph Hellwig
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