From: afzal mohammed <afzal.mohd.ma@gmail.com> To: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@armlinux.org.uk>, Linux ARM <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: ARM: vmsplit 4g/4g Date: Mon, 8 Jun 2020 16:48:34 +0530 [thread overview] Message-ID: <20200608111834.GB5736@afzalpc> (raw) In-Reply-To: <CAK8P3a2=o6RkONUoHTaR-2jpXg-wa-YnCYi0a4gAknYmvu8X7Q@mail.gmail.com> Hi, On Sun, Jun 07, 2020 at 09:26:26PM +0200, Arnd Bergmann wrote: > I think you have to use get_user_pages() though instead of > get_user_pages_fast(), > in order to be able to check the permission bits to prevent doing a > copy_to_user() > into read-only mappings. i was not aware of this, is it documented somewhere ?, afaiu, difference b/n get_user_pages_fast() & get_user_pages() is that fast version will try to pin pages w/o acquiring mmap_sem if possible. > Do you want me to review the uaccess patch to look for any missing > corner cases, or do you want to do the whole set of user access helpers > first? i will cleanup and probably post RFC initially for the changes handling copy_{from,to}_user() to get feedback. Regards afzal
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From: afzal mohammed <afzal.mohd.ma@gmail.com> To: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@armlinux.org.uk>, Linux ARM <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: ARM: vmsplit 4g/4g Date: Mon, 8 Jun 2020 16:48:34 +0530 [thread overview] Message-ID: <20200608111834.GB5736@afzalpc> (raw) In-Reply-To: <CAK8P3a2=o6RkONUoHTaR-2jpXg-wa-YnCYi0a4gAknYmvu8X7Q@mail.gmail.com> Hi, On Sun, Jun 07, 2020 at 09:26:26PM +0200, Arnd Bergmann wrote: > I think you have to use get_user_pages() though instead of > get_user_pages_fast(), > in order to be able to check the permission bits to prevent doing a > copy_to_user() > into read-only mappings. i was not aware of this, is it documented somewhere ?, afaiu, difference b/n get_user_pages_fast() & get_user_pages() is that fast version will try to pin pages w/o acquiring mmap_sem if possible. > Do you want me to review the uaccess patch to look for any missing > corner cases, or do you want to do the whole set of user access helpers > first? i will cleanup and probably post RFC initially for the changes handling copy_{from,to}_user() to get feedback. Regards afzal _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-06-08 11:18 UTC|newest] Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-31 9:32 [PATCH 0/3] Highmem support for 32-bit RISC-V Eric Lin 2020-03-31 9:32 ` Eric Lin 2020-03-31 9:32 ` [PATCH 1/3] riscv/mm: Add pkmap region and CONFIG_HIGHMEM Eric Lin 2020-03-31 9:32 ` Eric Lin 2020-03-31 9:32 ` [PATCH 2/3] riscv/mm: Implement kmap() and kmap_atomic() Eric Lin 2020-03-31 9:32 ` Eric Lin 2020-03-31 9:32 ` [PATCH 3/3] riscv/mm: Add pkmap in print_vm_layout() Eric Lin 2020-03-31 9:32 ` Eric Lin 2020-04-02 9:31 ` [PATCH 0/3] Highmem support for 32-bit RISC-V Arnd Bergmann 2020-04-02 9:31 ` Arnd Bergmann 2020-04-08 3:51 ` Alan Kao 2020-04-08 3:51 ` Alan Kao 2020-04-08 14:40 ` Arnd Bergmann 2020-04-08 14:40 ` Arnd Bergmann 2020-04-14 15:17 ` afzal mohammed 2020-04-14 15:17 ` afzal mohammed 2020-04-14 19:29 ` Arnd Bergmann 2020-04-14 19:29 ` Arnd Bergmann 2020-04-15 13:54 ` afzal mohammed 2020-04-15 13:54 ` afzal mohammed 2020-05-03 14:50 ` afzal mohammed 2020-05-03 14:50 ` afzal mohammed 2020-05-03 20:20 ` Arnd Bergmann 2020-05-03 20:20 ` Arnd Bergmann 2020-05-04 9:10 ` afzal mohammed 2020-05-04 9:10 ` afzal mohammed 2020-05-04 9:10 ` afzal mohammed 2020-05-04 11:27 ` Arnd Bergmann 2020-05-04 11:27 ` Arnd Bergmann 2020-05-04 11:27 ` Arnd Bergmann 2020-05-11 14:21 ` ARM: static kernel in vmalloc space (was Re: [PATCH 0/3] Highmem support for 32-bit RISC-V) afzal mohammed 2020-05-11 14:21 ` afzal mohammed 2020-05-11 15:29 ` Arnd Bergmann 2020-05-11 15:29 ` Arnd Bergmann 2020-05-12 10:47 ` ARM: static kernel in vmalloc space afzal mohammed 2020-05-12 10:47 ` afzal mohammed 2020-05-12 19:49 ` Arnd Bergmann 2020-05-12 19:49 ` Arnd Bergmann 2020-05-14 11:17 ` afzal mohammed 2020-05-14 11:17 ` afzal mohammed 2020-05-14 12:41 ` Arnd Bergmann 2020-05-14 12:41 ` Arnd Bergmann 2020-05-14 13:35 ` afzal mohammed 2020-05-14 13:35 ` afzal mohammed 2020-05-14 14:44 ` afzal mohammed 2020-05-14 14:44 ` afzal mohammed 2020-05-14 15:32 ` Arnd Bergmann 2020-05-14 15:32 ` Arnd Bergmann 2020-05-16 6:06 ` afzal mohammed 2020-05-16 6:06 ` afzal mohammed 2020-05-16 7:35 ` Arnd Bergmann 2020-05-16 7:35 ` Arnd Bergmann 2020-06-07 12:59 ` ARM: vmsplit 4g/4g afzal mohammed 2020-06-07 16:11 ` Russell King - ARM Linux admin 2020-06-07 16:11 ` Russell King - ARM Linux admin 2020-06-08 11:09 ` afzal mohammed 2020-06-08 11:09 ` afzal mohammed 2020-06-10 10:10 ` Linus Walleij 2020-06-10 10:10 ` Linus Walleij 2020-06-12 10:25 ` afzal mohammed 2020-06-12 10:25 ` afzal mohammed 2020-06-15 9:11 ` Linus Walleij 2020-06-15 9:11 ` Linus Walleij 2020-06-15 10:01 ` afzal mohammed 2020-06-15 10:01 ` afzal mohammed 2020-06-07 19:26 ` Arnd Bergmann 2020-06-07 19:26 ` Arnd Bergmann 2020-06-08 11:18 ` afzal mohammed [this message] 2020-06-08 11:18 ` afzal mohammed 2020-06-08 14:43 ` Arnd Bergmann 2020-06-08 14:43 ` Arnd Bergmann 2020-06-08 15:17 ` afzal mohammed 2020-06-08 15:17 ` afzal mohammed 2020-06-09 12:15 ` afzal mohammed 2020-06-09 12:15 ` afzal mohammed 2020-06-09 14:22 ` Arnd Bergmann 2020-06-09 14:22 ` Arnd Bergmann 2020-05-14 16:25 ` ARM: static kernel in vmalloc space Russell King - ARM Linux admin 2020-05-14 16:25 ` Russell King - ARM Linux admin 2020-05-14 21:12 ` Arnd Bergmann 2020-05-14 21:12 ` Arnd Bergmann 2020-05-14 23:40 ` Russell King - ARM Linux admin 2020-05-14 23:40 ` Russell King - ARM Linux admin 2020-05-15 15:41 ` Arnd Bergmann 2020-05-15 15:41 ` Arnd Bergmann 2020-07-30 9:33 ` Linus Walleij 2020-07-30 9:33 ` Linus Walleij 2020-07-30 10:17 ` Arnd Bergmann 2020-07-30 10:17 ` Arnd Bergmann
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