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Groups > linux.kernel > #1550230
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: sg_io HARDENED_USERCOPY_PAGESPAN trace |
| Date | 2017-01-03 22:50 +0100 |
| Message-ID | <sVF7X-3Mr-19@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <sTDMZ-3Kv-5@gated-at.bofh.it> <sTL7Q-8pB-19@gated-at.bofh.it> <sU5zA-4WJ-15@gated-at.bofh.it> <sU6YF-5Yf-5@gated-at.bofh.it> <sU78m-63l-21@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Dec 30, 2016 at 7:10 AM, Christoph Hellwig <hch@infradead.org> wrote: > On Fri, Dec 30, 2016 at 10:01:39AM -0500, Dave Jones wrote: >> I threw this debug printk into the pagespan code to see what exactly >> it was complaining about.. >> >> ptr:ffff88042614cff8 end:ffff88042614d003 n:c >> >> so it was copying 12 bytes that spanned two pages. >> >From my reading of the config option help text, this thing is >> complaining that wasn't allocated with __GFP_COMP maybe ? There are a lot of cases of "missing" __GFP_COMP, which is why HARDENED_USERCOPY_PAGESPAN defaults to "n". > If this is on a devie using blk-mq the block core will use high > order allocations (as high as possible) to allocate the requests > for each queue, so struct request could very well span multiple > pages. But I don't see what __GFP_COMP would have to do with > user copy annoations. As all requests for a queue are freed > togeth again there is no point in setting __GFP_COMP for the > request allocations. Does it hurt anything to mark these pages as allocated "together" via __GFP_COMP? -Kees -- Kees Cook Nexus Security
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sg_io HARDENED_USERCOPY_PAGESPAN trace Dave Jones <davej@codemonkey.org.uk> - 2016-12-28 22:50 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Dave Jones <davej@codemonkey.org.uk> - 2016-12-29 16:50 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Christoph Hellwig <hch@infradead.org> - 2016-12-30 14:40 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Dave Jones <davej@codemonkey.org.uk> - 2016-12-30 16:10 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Christoph Hellwig <hch@infradead.org> - 2016-12-30 16:20 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Kees Cook <keescook@chromium.org> - 2017-01-03 22:50 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Christoph Hellwig <hch@infradead.org> - 2017-01-08 10:50 +0100
Re: sg_io HARDENED_USERCOPY_PAGESPAN trace Christoph Hellwig <hch@infradead.org> - 2016-12-29 09:00 +0100
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