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[66.29.188.166]) by smtp.gmail.com with ESMTPSA id j14sm12974386pfa.57.2019.04.03.08.39.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Apr 2019 08:39:56 -0700 (PDT) Subject: Re: [PATCH 2/2] arch: add pidfd and io_uring syscalls everywhere To: Will Deacon Cc: Michael Ellerman , Arnd Bergmann , Andrew Morton , Richard Henderson , Ivan Kokshaysky , Matt Turner , Russell King , Catalin Marinas , Tony Luck , Fenghua Yu , Geert Uytterhoeven , Michal Simek , Ralf Baechle , Paul Burton , James Hogan , "James E . J . Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , Rich Felker , "David S . Miller" , Max Filippov , Firoz Khan , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org References: <20190325143521.34928-1-arnd@arndb.de> <20190325144737.703921-1-arnd@arndb.de> <87tvff24a1.fsf@concordia.ellerman.id.au> <20190403111134.GA7159@fuggles.cambridge.arm.com> <9d673dfd-0051-3676-653e-6376430d73dd@kernel.dk> <20190403151932.GA16866@fuggles.cambridge.arm.com> From: Jens Axboe Message-ID: <032faa2f-6317-75b6-8514-076ef1a244e8@kernel.dk> Date: Wed, 3 Apr 2019 09:39:52 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190403151932.GA16866@fuggles.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/3/19 9:19 AM, Will Deacon wrote: > 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@autoplooker:~/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. Does this help? diff --git a/fs/io_uring.c b/fs/io_uring.c index bbdbd56cf2ac..07d6ef195d05 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2215,6 +2215,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg, fput(ctx->user_files[i]); kfree(ctx->user_files); + ctx->user_files = NULL; ctx->nr_user_files = 0; return ret; } -- Jens Axboe