---------- Forwarded message ---------- From: Kyungtae Kim <kt0...@gmail.com> Date: Fri, May 11, 2018 at 11:38 AM Subject: KASAN: use-after-free Write in write_mem To: a...@arndb.de, gre...@linuxfoundation.org, linux-kernel@vger.kernel.org Cc: Byoungyoung Lee <lifeasag...@gmail.com>, DaeLyong Jeong <threeear...@gmail.com>
We report the crash: "KASAN: use-after-free Write in write_mem" This crash was found in v4.17-rc3. Specifically, memory access (write operation) is invalid, and it is detected by KASAN. C repro code: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/repro-3c6e1.c kernel config: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/kernel-config-v4.17-rc3 Crash log: ============================================================ Write of size 4096 at addr ffff880000010000 by task syz-executor1/3358 CPU: 0 PID: 3358 Comm: syz-executor1 Not tainted 4.17.0-rc3 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xc7/0x138 lib/dump_stack.c:113 print_address_description+0x6a/0x280 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x22f/0x350 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13b/0x1a0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 _copy_from_user+0xb7/0x100 lib/usercopy.c:12 copy_from_user include/linux/uaccess.h:147 [inline] write_mem+0x8f/0x190 drivers/char/mem.c:240 __vfs_write+0x10d/0x610 fs/read_write.c:485 vfs_write+0x187/0x500 fs/read_write.c:549 ksys_write+0xd4/0x1a0 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0xa4/0x460 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007f6f7f254c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f6f7f2556cc RCX: 00000000004497b9 RDX: 00000000ffffffad RSI: 0000000020000000 RDI: 0000000000000013 RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000009ee8 R14: 00000000006f0f88 R15: 00007f6f7f255700 The buggy address belongs to the page: page:ffffea0000000400 count:0 mapcount:-127 mapping:0000000000000000 index:0x0 flags: 0x0() raw: 0000000000000000 0000000000000000 0000000000000000 00000000ffffff80 raw: ffff88013fff91e0 ffffea0000002020 0000000000000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88000000ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88000000ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff880000010000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff880000010080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff880000010100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ============================================================ Thanks, Kyungtae Kim