linux-kernel - UBSAN: Undefined behaviour in fs/fs-writeback.c:1586:18

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Message-ID: <644b1741-9b47-97ae-7bc3-f18bc25bf22b@gmx.de>
Date:   Thu, 6 Jul 2017 18:49:41 +0200
From:   Toralf Förster <toralf.foerster@....de>
To:     linux-fsdevel <linux-fsdevel@...r.kernel.org>
Cc:     Linux Kernel <linux-kernel@...r.kernel.org>
Subject: UBSAN: Undefined behaviour in fs/fs-writeback.c:1586:18

Got that at a hardened Gentoo Linux server with 4.12.0 (for the first time) at a BTRFS logical volume occuping about 4/9 of a 5 TB volume group after an uptime of about 2 days :
Had issues with processes accessing files at that volume now too.

Jul  6 15:33:53 mr-fox kernel: [158695.417132] ================================================================================
Jul  6 15:33:53 mr-fox kernel: [158695.417137] UBSAN: Undefined behaviour in fs/fs-writeback.c:1586:18
Jul  6 15:33:53 mr-fox kernel: [158695.417139] signed integer overflow:
Jul  6 15:33:53 mr-fox kernel: [158695.417140] 9223372036854775807 - -327 cannot be represented in type 'long int'
Jul  6 15:33:53 mr-fox kernel: [158695.417143] CPU: 9 PID: 20027 Comm: kworker/u24:16 Not tainted 4.12.0 #1
Jul  6 15:33:53 mr-fox kernel: [158695.417144] Hardware name:                  /DX79TO, BIOS SIX7910J.86A.0650.2014.0307.0138 03/07/2014
Jul  6 15:33:53 mr-fox kernel: [158695.417151] Workqueue: writeback wb_workfn (flush-btrfs-1)
Jul  6 15:33:53 mr-fox kernel: [158695.417153] Call Trace:
Jul  6 15:33:53 mr-fox kernel: [158695.417158]  dump_stack+0x60/0x9a
Jul  6 15:33:53 mr-fox kernel: [158695.417161]  ubsan_epilogue+0xd/0x40
Jul  6 15:33:53 mr-fox kernel: [158695.417163]  handle_overflow+0xc8/0xf0
Jul  6 15:33:53 mr-fox kernel: [158695.417165]  ? __writeback_single_inode+0x17c/0x560
Jul  6 15:33:53 mr-fox kernel: [158695.417167]  __ubsan_handle_sub_overflow+0xe/0x10
Jul  6 15:33:53 mr-fox kernel: [158695.417169]  writeback_sb_inodes+0x7a3/0x850
Jul  6 15:33:53 mr-fox kernel: [158695.417171]  __writeback_inodes_wb+0xa0/0x140
Jul  6 15:33:53 mr-fox kernel: [158695.417172]  wb_writeback+0x35c/0x4d0
Jul  6 15:33:53 mr-fox kernel: [158695.417174]  wb_workfn+0x25b/0x6b0
Jul  6 15:33:53 mr-fox kernel: [158695.417175]  ? wb_workfn+0x25b/0x6b0
Jul  6 15:33:53 mr-fox kernel: [158695.417178]  process_one_work+0x225/0x7d0
Jul  6 15:33:53 mr-fox kernel: [158695.417180]  worker_thread+0x6b/0x500
Jul  6 15:33:53 mr-fox kernel: [158695.417182]  kthread+0x168/0x240
Jul  6 15:33:53 mr-fox kernel: [158695.417184]  ? process_one_work+0x7d0/0x7d0
Jul  6 15:33:53 mr-fox kernel: [158695.417185]  ? __kthread_create_on_node+0x1c0/0x1c0
Jul  6 15:33:53 mr-fox kernel: [158695.417189]  ret_from_fork+0x22/0x30
Jul  6 15:33:53 mr-fox kernel: [158695.417190] ================================================================================
Jul  6 15:33:53 mr-fox kernel: [158695.417193] ================================================================================
Jul  6 15:33:53 mr-fox kernel: [158695.417194] UBSAN: Undefined behaviour in fs/fs-writeback.c:1797:9
Jul  6 15:33:53 mr-fox kernel: [158695.417195] signed integer overflow:
Jul  6 15:33:53 mr-fox kernel: [158695.417196] 9223372036854775807 - -9223372036854775482 cannot be represented in type 'long int'
Jul  6 15:33:53 mr-fox kernel: [158695.417198] CPU: 9 PID: 20027 Comm: kworker/u24:16 Not tainted 4.12.0 #1
Jul  6 15:33:53 mr-fox kernel: [158695.417199] Hardware name:                  /DX79TO, BIOS SIX7910J.86A.0650.2014.0307.0138 03/07/2014
Jul  6 15:33:53 mr-fox kernel: [158695.417201] Workqueue: writeback wb_workfn (flush-btrfs-1)
Jul  6 15:33:53 mr-fox kernel: [158695.417203] Call Trace:
Jul  6 15:33:53 mr-fox kernel: [158695.417204]  dump_stack+0x60/0x9a
Jul  6 15:33:53 mr-fox kernel: [158695.417206]  ubsan_epilogue+0xd/0x40
Jul  6 15:33:53 mr-fox kernel: [158695.417208]  handle_overflow+0xc8/0xf0
Jul  6 15:33:53 mr-fox kernel: [158695.417210]  __ubsan_handle_sub_overflow+0xe/0x10
Jul  6 15:33:53 mr-fox kernel: [158695.417211]  wb_writeback+0x3a7/0x4d0
Jul  6 15:33:53 mr-fox kernel: [158695.417213]  wb_workfn+0x25b/0x6b0
Jul  6 15:33:53 mr-fox kernel: [158695.417214]  ? wb_workfn+0x25b/0x6b0
Jul  6 15:33:53 mr-fox kernel: [158695.417216]  process_one_work+0x225/0x7d0
Jul  6 15:33:53 mr-fox kernel: [158695.417218]  worker_thread+0x6b/0x500
Jul  6 15:33:53 mr-fox kernel: [158695.417219]  kthread+0x168/0x240
Jul  6 15:33:53 mr-fox kernel: [158695.417221]  ? process_one_work+0x7d0/0x7d0
Jul  6 15:33:53 mr-fox kernel: [158695.417222]  ? __kthread_create_on_node+0x1c0/0x1c0
Jul  6 15:33:53 mr-fox kernel: [158695.417224]  ret_from_fork+0x22/0x30
Jul  6 15:33:53 mr-fox kernel: [158695.417225] ================================================================================


-- 
Toralf
PGP C4EACDDE 0076E94E