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From: David Laight <David.Laight@ACULAB.COM>
To: 'Christoph Hellwig' <hch@lst.de>,
	Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>, Arnd Bergmann <arnd@arndb.de>,
	David Howells <dhowells@redhat.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
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	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>
Subject: RE: [PATCH 05/11] iov_iter: merge the compat case into rw_copy_check_uvector
Date: Fri, 8 Jan 2021 11:49:27 +0000	[thread overview]
Message-ID: <7167a94511a84f30b18733d56007a7a5@AcuMS.aculab.com> (raw)
In-Reply-To: <20200921143434.707844-6-hch@lst.de>

From: Christoph Hellwig <hch@lst.de>
> Sent: 21 September 2020 15:34
> 
> Stop duplicating the iovec verify code, and instead add add a
> __import_iovec helper that does the whole verify and import, but takes
> a bool compat to decided on the native or compat layout.  This also
> ends up massively simplifying the calling conventions.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  lib/iov_iter.c | 195 ++++++++++++++++++-------------------------------
>  1 file changed, 70 insertions(+), 125 deletions(-)
> 
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index a64867501a7483..8bfa47b63d39aa 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -10,6 +10,7 @@
>  #include <net/checksum.h>
>  #include <linux/scatterlist.h>
>  #include <linux/instrumented.h>
> +#include <linux/compat.h>
> 
>  #define PIPE_PARANOIA /* for now */
> 
> @@ -1650,43 +1651,76 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
>  }
>  EXPORT_SYMBOL(dup_iter);
> 
> -static ssize_t rw_copy_check_uvector(int type,
> -		const struct iovec __user *uvector, unsigned long nr_segs,
> -		unsigned long fast_segs, struct iovec *fast_pointer,
> -		struct iovec **ret_pointer)
> +static int compat_copy_iovecs_from_user(struct iovec *iov,
> +		const struct iovec __user *uvector, unsigned long nr_segs)
> +{
> +	const struct compat_iovec __user *uiov =
> +		(const struct compat_iovec __user *)uvector;
> +	unsigned long i;
> +	int ret = -EFAULT;
> +
> +	if (!user_access_begin(uvector, nr_segs * sizeof(*uvector)))
> +		return -EFAULT;

I little bit late, but the above isn't quite right.
It should be sizeof(*iouv) - the length is double what it should be.

Not that access_ok() can fail for compat addresses
and the extra length won't matter for architectures that
need the address/length to open an address hole into userspace.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  parent reply	other threads:[~2021-01-08 11:51 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21 14:34 let import_iovec deal with compat_iovecs as well v2 Christoph Hellwig
2020-09-21 14:34 ` [PATCH 01/11] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-21 14:34 ` [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw() Christoph Hellwig
2020-09-21 14:48   ` Matthew Wilcox
2020-09-21 15:02   ` Al Viro
2020-09-21 15:21     ` David Laight
2020-09-21 15:29       ` Al Viro
2020-09-21 15:44         ` David Laight
2020-09-21 16:27           ` Al Viro
2020-09-21 16:12         ` Christoph Hellwig
2020-09-21 14:34 ` [PATCH 03/11] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c and mark it static Christoph Hellwig
2020-09-21 14:34 ` [PATCH 04/11] iov_iter: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:05   ` David Laight
2020-09-21 15:11     ` Al Viro
2020-09-21 15:26       ` David Laight
2020-09-21 15:07   ` Al Viro
2020-09-21 14:34 ` [PATCH 05/11] iov_iter: merge the compat case into rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:14   ` Al Viro
2021-01-08 11:49   ` David Laight [this message]
2020-09-21 14:34 ` [PATCH 06/11] iov_iter: handle the compat case in import_iovec Christoph Hellwig
2020-09-21 15:20   ` Al Viro
2020-09-21 14:34 ` [PATCH 07/11] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-21 14:34 ` [PATCH 08/11] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-21 14:34 ` [PATCH 09/11] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-21 14:34 ` [PATCH 10/11] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-21 14:34 ` [PATCH 11/11] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig

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