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Message-ID: <20190403151932.GA16866@fuggles.cambridge.arm.com>
Date: Wed, 3 Apr 2019 16:19:32 +0100
From: Will Deacon <will.deacon@....com>
To: Jens Axboe <axboe@...nel.dk>
Cc: Michael Ellerman <mpe@...erman.id.au>,
Arnd Bergmann <arnd@...db.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Richard Henderson <rth@...ddle.net>,
Ivan Kokshaysky <ink@...assic.park.msu.ru>,
Matt Turner <mattst88@...il.com>,
Russell King <linux@...linux.org.uk>,
Catalin Marinas <catalin.marinas@....com>,
Tony Luck <tony.luck@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Michal Simek <monstr@...str.eu>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>,
James Hogan <jhogan@...nel.org>,
"James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Rich Felker <dalias@...c.org>,
"David S . Miller" <davem@...emloft.net>,
Max Filippov <jcmvbkbc@...il.com>,
Firoz Khan <firoz.khan@...aro.org>,
linux-alpha@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
sparclinux@...r.kernel.org
Subject: Re: [PATCH 2/2] arch: add pidfd and io_uring syscalls everywhere
Hi Jens,
On Wed, Apr 03, 2019 at 07:49:26AM -0600, Jens Axboe wrote:
> On 4/3/19 5:11 AM, Will Deacon wrote:
> > will@...oplooker:~/liburing/test$ ./io_uring_register
> > RELIMIT_MEMLOCK: 67108864 (67108864)
> > [ 35.477875] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070
> > [ 35.478969] Mem abort info:
> > [ 35.479296] ESR = 0x96000004
> > [ 35.479785] Exception class = DABT (current EL), IL = 32 bits
> > [ 35.480528] SET = 0, FnV = 0
> > [ 35.480980] EA = 0, S1PTW = 0
> > [ 35.481345] Data abort info:
> > [ 35.481680] ISV = 0, ISS = 0x00000004
> > [ 35.482267] CM = 0, WnR = 0
> > [ 35.482618] user pgtable: 4k pages, 48-bit VAs, pgdp = (____ptrval____)
> > [ 35.483486] [0000000000000070] pgd=0000000000000000
> > [ 35.484041] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> > [ 35.484788] Modules linked in:
> > [ 35.485311] CPU: 113 PID: 3973 Comm: io_uring_regist Not tainted 5.1.0-rc3-00012-g40b114779944 #1
> > [ 35.486712] Hardware name: linux,dummy-virt (DT)
> > [ 35.487450] pstate: 20400005 (nzCv daif +PAN -UAO)
> > [ 35.488228] pc : link_pwq+0x10/0x60
> > [ 35.488794] lr : apply_wqattrs_commit+0xe0/0x118
> > [ 35.489550] sp : ffff000017e2bbc0
>
> Huh, this looks odd, it's crashing inside the wq setup.
Enabling KASAN seems to indicate a double-free, which may well be related.
Will
[ 149.890370] ==================================================================
[ 149.891266] BUG: KASAN: double-free or invalid-free in io_sqe_files_unregister+0xa8/0x140
[ 149.892218]
[ 149.892411] CPU: 113 PID: 3974 Comm: io_uring_regist Tainted: G B 5.1.0-rc3-00012-g40b114779944 #3
[ 149.893623] Hardware name: linux,dummy-virt (DT)
[ 149.894169] Call trace:
[ 149.894539] dump_backtrace+0x0/0x228
[ 149.895172] show_stack+0x14/0x20
[ 149.895747] dump_stack+0xe8/0x124
[ 149.896335] print_address_description+0x60/0x258
[ 149.897148] kasan_report_invalid_free+0x78/0xb8
[ 149.897936] __kasan_slab_free+0x1fc/0x228
[ 149.898641] kasan_slab_free+0x10/0x18
[ 149.899283] kfree+0x70/0x1f8
[ 149.899798] io_sqe_files_unregister+0xa8/0x140
[ 149.900574] io_ring_ctx_wait_and_kill+0x190/0x3c0
[ 149.901402] io_uring_release+0x2c/0x48
[ 149.902068] __fput+0x18c/0x510
[ 149.902612] ____fput+0xc/0x18
[ 149.903146] task_work_run+0xf0/0x148
[ 149.903778] do_notify_resume+0x554/0x748
[ 149.904467] work_pending+0x8/0x10
[ 149.905060]
[ 149.905331] Allocated by task 3974:
[ 149.905934] __kasan_kmalloc.isra.0.part.1+0x48/0xf8
[ 149.906786] __kasan_kmalloc.isra.0+0xb8/0xd8
[ 149.907531] kasan_kmalloc+0xc/0x18
[ 149.908134] __kmalloc+0x168/0x248
[ 149.908724] __arm64_sys_io_uring_register+0x2b8/0x15a8
[ 149.909622] el0_svc_common+0x100/0x258
[ 149.910281] el0_svc_handler+0x48/0xc0
[ 149.910928] el0_svc+0x8/0xc
[ 149.911425]
[ 149.911696] Freed by task 3974:
[ 149.912242] __kasan_slab_free+0x114/0x228
[ 149.912955] kasan_slab_free+0x10/0x18
[ 149.913602] kfree+0x70/0x1f8
[ 149.914118] __arm64_sys_io_uring_register+0xc2c/0x15a8
[ 149.915009] el0_svc_common+0x100/0x258
[ 149.915670] el0_svc_handler+0x48/0xc0
[ 149.916317] el0_svc+0x8/0xc
[ 149.916817]
[ 149.917101] The buggy address belongs to the object at ffff8004ce07ed00
[ 149.917101] which belongs to the cache kmalloc-128 of size 128
[ 149.919197] The buggy address is located 0 bytes inside of
[ 149.919197] 128-byte region [ffff8004ce07ed00, ffff8004ce07ed80)
[ 149.921142] The buggy address belongs to the page:
[ 149.921953] page:ffff7e0013381f00 count:1 mapcount:0 mapping:ffff800503417c00 index:0x0 compound_mapcount: 0
[ 149.923595] flags: 0x1ffff00000010200(slab|head)
[ 149.924388] raw: 1ffff00000010200 dead000000000100 dead000000000200 ffff800503417c00
[ 149.925706] raw: 0000000000000000 0000000080400040 00000001ffffffff 0000000000000000
[ 149.927011] page dumped because: kasan: bad access detected
[ 149.927956]
[ 149.928224] Memory state around the buggy address:
[ 149.929054] ffff8004ce07ec00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
[ 149.930274] ffff8004ce07ec80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 149.931494] >ffff8004ce07ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 149.932712] ^
[ 149.933281] ffff8004ce07ed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 149.934508] ffff8004ce07ee00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 149.935725] ==================================================================
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