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([2620:15c:2cd:203:5cdc:422c:7b28:ebb5]) by smtp.gmail.com with ESMTPSA id p24sm27703575pfk.155.2018.12.19.15.24.46 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 19 Dec 2018 15:24:46 -0800 (PST) Message-ID: <1545261885.185366.488.camel@acm.org> Subject: v4.20-rc6: Sporadic use-after-free in bt_iter() From: Bart Van Assche To: "linux-block@vger.kernel.org" Date: Wed, 19 Dec 2018 15:24:45 -0800 Content-Type: text/plain; charset="UTF-7" X-Mailer: Evolution 3.26.2-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello, If I run the srp blktests in a loop then I see the below call stack appearing sporadically. I have not yet had the time to analyze this but I'm reporting this here in case someone else would already have had a look at this. Bart. +AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9 BUG: KASAN: use-after-free in bt+AF8-iter+-0x86/0xf0 Read of size 8 at addr ffff88803b335240 by task fio/21412 CPU: 0 PID: 21412 Comm: fio Tainted: G W 4.20.0-rc6-dbg+- +ACM-3 Hardware name: QEMU Standard PC (i440FX +- PIIX, 1996), BIOS 1.10.2-1 04/01/2014 Call Trace: dump+AF8-stack+-0x86/0xca print+AF8-address+AF8-description+-0x71/0x239 kasan+AF8-report.cold.5+-0x242/0x301 +AF8AXw-asan+AF8-load8+-0x54/0x90 bt+AF8-iter+-0x86/0xf0 blk+AF8-mq+AF8-queue+AF8-tag+AF8-busy+AF8-iter+-0x373/0x5e0 blk+AF8-mq+AF8-in+AF8-flight+-0x96/0xb0 part+AF8-in+AF8-flight+-0x40/0x140 part+AF8-round+AF8-stats+-0x18e/0x370 blk+AF8-account+AF8-io+AF8-start+-0x3d7/0x670 blk+AF8-mq+AF8-bio+AF8-to+AF8-request+-0x19c/0x3a0 blk+AF8-mq+AF8-make+AF8-request+-0x7a9/0xcb0 generic+AF8-make+AF8-request+-0x41d/0x960 submit+AF8-bio+-0x9b/0x250 do+AF8-blockdev+AF8-direct+AF8-IO+-0x435c/0x4c70 +AF8AXw-blockdev+AF8-direct+AF8-IO+-0x79/0x88 ext4+AF8-direct+AF8-IO+-0x46c/0xc00 generic+AF8-file+AF8-direct+AF8-write+-0x119/0x210 +AF8AXw-generic+AF8-file+AF8-write+AF8-iter+-0x11c/0x280 ext4+AF8-file+AF8-write+AF8-iter+-0x1b8/0x6f0 aio+AF8-write+-0x204/0x310 io+AF8-submit+AF8-one+-0x9d3/0xe80 +AF8AXw-x64+AF8-sys+AF8-io+AF8-submit+-0x115/0x340 do+AF8-syscall+AF8-64+-0x71/0x210 entry+AF8-SYSCALL+AF8-64+AF8-after+AF8-hwframe+-0x49/0xbe RIP: 0033:0x7f02cf043219 Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 +ADw-48+AD4 3d 01 f0 ff ff 73 01 c3 48 8b 0d 47 fc 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007f02a1df78b8 EFLAGS: 00000246 ORIG+AF8-RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 00007f02a1df8ef8 RCX: 00007f02cf043219 RDX: 00007f029804a7c0 RSI: 0000000000000001 RDI: 00007f02c4f67000 RBP: 00007f02c4f67000 R08: 00007f0298007af0 R09: 00007f02a362f0f0 R10: 00007f029804a9c0 R11: 0000000000000246 R12: 0000000000000001 R13: 0000000000000000 R14: 00007f029804a7c0 R15: 00007f0298049f60 The buggy address belongs to the page: page:ffffea0000eccd40 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x1fff000000000000() raw: 1fff000000000000 0000000000000000 ffffffff00ec0201 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88803b335100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88803b335180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff +AD4-ffff88803b335200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff +AF4 ffff88803b335280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88803b335300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff +AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9AD0APQA9-