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Subject: Re: [PATCH] mpt3sas: Don't overreach ioc->reply_post[] during
 initialization
To: Calvin Owens <calvinowens@fb.com>,
        Sathya Prakash <sathya.prakash@broadcom.com>,
        Chaitra P B <chaitra.basappa@broadcom.com>,
        Suganath Prabu Subramani 
	<suganath-prabu.subramani@broadcom.com>,
        "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
References: <df80b371ec5e56ecd65be161acdc34c0f2964d2e.1458327050.git.calvinowens@fb.com>
CC: <MPT-FusionLinux.pdl@broadcom.com>, <linux-scsi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <kernel-team@fb.com>
From: Jens Axboe <axboe@fb.com>
Message-ID: <56F1775E.3020500@fb.com>
Date: Tue, 22 Mar 2016 10:48:30 -0600
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On 03/18/2016 01:45 PM, Calvin Owens wrote:
> In _base_make_ioc_operational(), we walk ioc->reply_queue_list and pull
> a pointer out of successive elements of ioc->reply_post[] for each entry
> in that list if RDPQ is enabled.
>
> Since the code pulls the pointer for the next iteration at the bottom of
> the loop, it triggers the a KASAN dump on the final iteration:
>
>      BUG: KASAN: slab-out-of-bounds in _base_make_ioc_operational+0x47b7/0x47e0 [mpt3sas] at addr ffff880754816ab0
>      Read of size 8 by task modprobe/305
>      <snip>
>      Call Trace:
>       [<ffffffff81dfc591>] dump_stack+0x4d/0x6c
>       [<ffffffff814c9689>] print_trailer+0xf9/0x150
>       [<ffffffff814ceda4>] object_err+0x34/0x40
>       [<ffffffff814d1231>] kasan_report_error+0x221/0x530
>       [<ffffffff814d1673>] __asan_report_load8_noabort+0x43/0x50
>       [<ffffffffa0043637>] _base_make_ioc_operational+0x47b7/0x47e0 [mpt3sas]
>       [<ffffffffa0049a51>] mpt3sas_base_attach+0x1991/0x2120 [mpt3sas]
>       [<ffffffffa0053c93>] _scsih_probe+0xeb3/0x16b0 [mpt3sas]
>       [<ffffffff81ebd047>] local_pci_probe+0xc7/0x170
>       [<ffffffff81ebf2cf>] pci_device_probe+0x20f/0x290
>       [<ffffffff820d50cd>] really_probe+0x17d/0x600
>       [<ffffffff820d56a3>] __driver_attach+0x153/0x190
>       [<ffffffff820cffac>] bus_for_each_dev+0x11c/0x1a0
>       [<ffffffff820d421d>] driver_attach+0x3d/0x50
>       [<ffffffff820d378a>] bus_add_driver+0x44a/0x5f0
>       [<ffffffff820d666c>] driver_register+0x18c/0x3b0
>       [<ffffffff81ebcb76>] __pci_register_driver+0x156/0x200
>       [<ffffffffa00c8135>] _mpt3sas_init+0x135/0x1000 [mpt3sas]
>       [<ffffffff81000423>] do_one_initcall+0x113/0x2b0
>       [<ffffffff813caa5a>] do_init_module+0x1d0/0x4d8
>       [<ffffffff81273909>] load_module+0x6729/0x8dc0
>       [<ffffffff81276123>] SYSC_init_module+0x183/0x1a0
>       [<ffffffff8127625e>] SyS_init_module+0xe/0x10
>       [<ffffffff828fe7d7>] entry_SYSCALL_64_fastpath+0x12/0x6a
>
> Fix this by pulling the value at the beginning of the loop.
>
> Signed-off-by: Calvin Owens <calvinowens@fb.com>

Looks good to me.

Reviewed-by: Jens Axboe <axboe@fb.com>

-- 
Jens Axboe