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From: Christoph Hellwig <hch@lst.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	broonie@kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-next@vger.kernel.org, mhocko@suse.cz,
	mm-commits@vger.kernel.org, sfr@canb.auug.org.au,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	viro@ZenIV.linux.org.uk, hch@lst.de, x86@kernel.org
Subject: Re: mmotm 2020-05-13-20-30 uploaded (objtool warnings)
Date: Fri, 29 May 2020 15:57:51 +0200	[thread overview]
Message-ID: <20200529135750.GA1580@lst.de> (raw)
In-Reply-To: <20200528172005.GP2483@worktop.programming.kicks-ass.net>

On Thu, May 28, 2020 at 07:20:05PM +0200, Peter Zijlstra wrote:
> > on x86_64:
> > 
> > arch/x86/lib/csum-wrappers_64.o: warning: objtool: csum_and_copy_from_user()+0x2a4: call to memset() with UACCESS enabled
> > arch/x86/lib/csum-wrappers_64.o: warning: objtool: csum_and_copy_to_user()+0x243: return with UACCESS enabled
> 
> Urgh, that's horrible code. That's got plain stac()/clac() calls on
> instead of the regular uaccess APIs.

Does it?  If this is from the code in linux-next, then the code does a
user_access_begin/end in csum_and_copy_{from,to}_user, then uses
unsafe_{get,put}_user inside those function itself.  But then they call
csum_partial_copy_generic with the __user casted away, but without any
comment on why this is safe.

  reply	other threads:[~2020-05-29 13:57 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200513175005.1f4839360c18c0238df292d1@linux-foundation.org>
2020-05-14  3:31 ` mmotm 2020-05-13-20-30 uploaded Andrew Morton
2020-05-14 15:30   ` mmotm 2020-05-13-20-30 uploaded (gpu/drm/bridge/sil-sii8620) Randy Dunlap
2020-05-14 15:32   ` mmotm 2020-05-13-20-30 uploaded (objtool warnings) Randy Dunlap
2020-05-14 15:33     ` Randy Dunlap
2020-05-28 15:54     ` Josh Poimboeuf
2020-05-28 17:04       ` Josh Poimboeuf
2020-05-28 17:20     ` Peter Zijlstra
2020-05-29 13:57       ` Christoph Hellwig [this message]
2020-05-29 14:35         ` Peter Zijlstra
2020-05-29 14:53           ` Peter Zijlstra
2020-05-29 15:33             ` Peter Zijlstra
2020-05-29 16:05               ` Josh Poimboeuf
2020-05-29 16:12                 ` Peter Zijlstra
2020-05-29 16:50                   ` Josh Poimboeuf
2020-05-29 16:54                     ` Peter Zijlstra
2020-05-29 17:25                       ` [PATCH] x86/uaccess: Remove redundant likely/unlikely annotations Josh Poimboeuf
2020-05-29 18:29                         ` Randy Dunlap
2020-05-29 19:31                     ` mmotm 2020-05-13-20-30 uploaded (objtool warnings) Linus Torvalds
2020-05-29 20:08                       ` Al Viro
2020-05-29 20:14                         ` Al Viro
2020-05-15 23:30 ` mmotm 2020-05-15-16-29 uploaded Andrew Morton
2020-05-16  5:53   ` Stephen Rothwell
2020-05-18 23:15     ` Stephen Rothwell
2020-05-20  4:48 ` mmotm 2020-05-19-21-47 uploaded Andrew Morton
2020-05-22  3:43 ` mmotm 2020-05-21-20-42 uploaded Andrew Morton
2020-05-22 16:26   ` mmotm 2020-05-21-20-42 uploaded (atomisp) Randy Dunlap
2020-05-23  3:36 ` mmotm 2020-05-22-20-35 uploaded Andrew Morton
2020-05-23 15:08   ` mmotm 2020-05-22-20-35 uploaded (phy/intel/phy-intel-combo.c) Randy Dunlap

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