From: Dominique Martinet <asmadeus@codewreck.org>
To: v9fs-developer@lists.sourceforge.net
Cc: Dominique Martinet <dominique.martinet@cea.fr>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>, Greg Kurz <groug@kaod.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [V9fs-developer] [PATCH v2 2/2] net/9p: add a per-client fcall kmem_cache
Date: Thu, 2 Aug 2018 06:58:51 +0200 [thread overview]
Message-ID: <20180802045851.GA15564@nautica> (raw)
In-Reply-To: <1533177452-2165-2-git-send-email-asmadeus@codewreck.org>
Dominique Martinet wrote on Thu, Aug 02, 2018:
> [...]
> + clnt->fcall_cache = kmem_cache_create("9p-fcall-cache", clnt->msize,
> + 0, 0, NULL);
Well, my gut feeling that I'd need a v3 was right, after a bit more time
testing (slightly different setup), I got this warning:
Bad or missing usercopy whitelist? Kernel memory overwrite attempt
detected to SLUB object '9p-fcall-cache' (offset 23, size 55078)!
So this kmem_cache_create needs to change to kmem_cache_create_usercopy,
but I'm not sure how to best specify the range -- this warning was about
writing data to the buffer so a TWRITE:
size[4] Twrite tag[2] fid[4] offset[8] count[4] data[count]
(the data[count] part comes from user - this matches 4+1+2+4+8+4 = 23)
Similarily RREAD has data that can be copied to userspace, which has a
similar check:
size[4] Rread tag[2] count[4] data[count]
So I could hardcode offset = 4+1+2+4=11, usercopy size = msize - 11...
We have some P9_*HDR*SZ macros but none are really appropriate:
---
/* ample room for Twrite/Rread header */
#define P9_IOHDRSZ 24
/* Room for readdir header */
#define P9_READDIRHDRSZ 24
/* size of header for zero copy read/write */
#define P9_ZC_HDR_SZ 4096
---
It's actually been bugging me for a while that I see hardcoded '7's for
9p main header size (len + msg type + tag) everywhere, I could add a
first P9_HDRSZ of 7 and use that + 4?
--
Dominique
next prev parent reply other threads:[~2018-08-02 4:59 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 21:02 [PATCH v2 0/6] 9p: Use IDRs more effectively Matthew Wilcox
2018-07-11 21:02 ` [PATCH v2 1/6] 9p: Fix comment on smp_wmb Matthew Wilcox
2018-07-12 11:55 ` [V9fs-developer] " Greg Kurz
2018-07-11 21:02 ` [PATCH v2 2/6] 9p: Change p9_fid_create calling convention Matthew Wilcox
2018-07-12 2:15 ` [V9fs-developer] " piaojun
2018-07-12 11:56 ` Greg Kurz
2018-07-13 1:18 ` jiangyiwen
2018-07-11 21:02 ` [PATCH v2 3/6] 9p: Replace the fidlist with an IDR Matthew Wilcox
2018-07-12 11:17 ` Dominique Martinet
2018-07-12 11:23 ` Matthew Wilcox
2018-07-12 11:30 ` Dominique Martinet
2018-07-13 2:05 ` [V9fs-developer] " jiangyiwen
2018-07-13 2:48 ` Matthew Wilcox
2018-07-11 21:02 ` [PATCH v2 4/6] 9p: Embed wait_queue_head into p9_req_t Matthew Wilcox
2018-07-12 14:36 ` [V9fs-developer] " Greg Kurz
2018-07-12 14:40 ` Dominique Martinet
2018-07-12 14:59 ` Greg Kurz
2018-07-11 21:02 ` [PATCH v2 5/6] 9p: Use a slab for allocating requests Matthew Wilcox
2018-07-18 10:05 ` Dominique Martinet
2018-07-18 11:49 ` Matthew Wilcox
2018-07-18 12:46 ` Dominique Martinet
2018-07-23 11:52 ` Greg Kurz
2018-07-23 12:25 ` Dominique Martinet
2018-07-23 14:24 ` Greg Kurz
2018-07-30 9:31 ` Dominique Martinet
2018-07-30 9:34 ` [PATCH 1/2] net/9p: embed fcall in req to round down buffer allocs Dominique Martinet
2018-07-30 9:34 ` [PATCH 2/2] net/9p: add a per-client fcall kmem_cache Dominique Martinet
2018-07-31 1:18 ` [V9fs-developer] " piaojun
2018-07-31 1:35 ` Dominique Martinet
2018-07-31 1:45 ` piaojun
2018-07-31 2:46 ` Matthew Wilcox
2018-07-31 4:17 ` Dominique Martinet
2018-08-01 14:28 ` [V9fs-developer] " Greg Kurz
2018-08-01 15:22 ` Dominique Martinet
2018-07-31 0:55 ` [V9fs-developer] [PATCH 1/2] net/9p: embed fcall in req to round down buffer allocs piaojun
2018-07-31 1:12 ` Dominique Martinet
2018-07-31 1:28 ` piaojun
2018-08-01 14:14 ` Greg Kurz
2018-08-01 14:38 ` Dominique Martinet
2018-08-01 15:03 ` Greg Kurz
2018-08-02 2:37 ` [PATCH v2 " Dominique Martinet
2018-08-02 2:37 ` [PATCH v2 2/2] net/9p: add a per-client fcall kmem_cache Dominique Martinet
2018-08-02 4:58 ` Dominique Martinet [this message]
2018-08-02 9:23 ` [PATCH v2 1/2] net/9p: embed fcall in req to round down buffer allocs Greg Kurz
2018-08-02 22:03 ` Dominique Martinet
2018-08-09 14:33 ` [PATCH v3 " Dominique Martinet
2018-08-09 14:33 ` [PATCH v3 2/2] net/9p: add a per-client fcall kmem_cache Dominique Martinet
2018-08-10 1:23 ` piaojun
2018-08-10 1:41 ` Dominique Martinet
2018-08-10 1:49 ` piaojun
2018-08-10 0:47 ` [PATCH v3 1/2] net/9p: embed fcall in req to round down buffer allocs piaojun
2018-07-11 21:02 ` [PATCH v2 6/6] 9p: Remove p9_idpool Matthew Wilcox
2018-07-11 23:37 ` [PATCH v2 0/6] 9p: Use IDRs more effectively Dominique Martinet
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