Re: [PATCH] scsi: ses: Fix out-of-bounds memory access in ses_enclosure_data_process()

From: Waiman Long
Date: Mon May 20 2019 - 10:44:13 EST


On 5/1/19 2:05 PM, Waiman Long wrote:
> KASAN has found a slab-out-of-bounds error in ses_enclosure_data_process().
>
> [ 27.298092] BUG: KASAN: slab-out-of-bounds in ses_enclosure_data_process+0x919/0xe80 [ses]
> [ 27.306407] Read of size 1 at addr ffff8807c99048b1 by task systemd-udevd/1563
> [ 27.315173] CPU: 18 PID: 1563 Comm: systemd-udevd Not tainted 4.18.0-80.23.el8.x86_64+debug #1
> [ 27.323835] Hardware name: HPE ProLiant XL450 Gen10/ProLiant XL450 Gen10, BIOS U40 10/02/2018
> [ 27.332410] Call Trace:
> :
> [ 27.348557] kasan_report.cold.6+0x92/0x1a6
> [ 27.352771] ses_enclosure_data_process+0x919/0xe80 [ses]
> [ 27.358211] ? kfree+0xd6/0x2e0
> [ 27.361376] ses_intf_add+0xa23/0xef1 [ses]
> [ 27.365590] ? class_dev_iter_next+0x6c/0xc0
> [ 27.370034] class_interface_register+0x298/0x400
> [ 27.374769] ? tsc_cs_mark_unstable+0x60/0x60
> [ 27.379163] ? class_dev_iter_exit+0x10/0x10
> [ 27.384857] ? 0xffffffffc0838000
> [ 27.389580] ses_init+0x12/0x1000 [ses]
> [ 27.394832] do_one_initcall+0xe9/0x5fd
> :
> [ 27.562322] Allocated by task 1563:
> [ 27.562330] kasan_kmalloc+0xbf/0xe0
> [ 27.569433] __kmalloc+0x150/0x360
> [ 27.572858] ses_intf_add+0x76a/0xef1 [ses]
> [ 27.577068] class_interface_register+0x298/0x400
> [ 27.581803] ses_init+0x12/0x1000 [ses]
> [ 27.587053] do_one_initcall+0xe9/0x5fd
> [ 27.592309] do_init_module+0x1f2/0x710
> [ 27.597564] load_module+0x3e19/0x5910
> [ 27.601336] __do_sys_init_module+0x1dd/0x260
> [ 27.606673] do_syscall_64+0xa5/0x4a0
> [ 27.610359] entry_SYSCALL_64_after_hwframe+0x6a/0xdf
> :
> [ 27.624932] The buggy address belongs to the object at ffff8807c9904400
> which belongs to the cache kmalloc-2048 of size 2048
> [ 27.637701] The buggy address is located 1201 bytes inside of
> 2048-byte region [ffff8807c9904400, ffff8807c9904c00)
> [ 27.649683] The buggy address belongs to the page:
> [ 27.654503] page:ffffea001f264000 count:1 mapcount:0 mapping:ffff880107c15d80 index:0x0 compound_mapcount: 0
> [ 27.664393] flags: 0x17ffffc0008100(slab|head)
> [ 27.668865] raw: 0017ffffc0008100 dead000000000100 dead000000000200 ffff880107c15d80
> [ 27.676656] raw: 0000000000000000 00000000800f000f 00000001ffffffff 0000000000000000
> [ 27.684444] page dumped because: kasan: bad access detected
>
> The out-of-bounds memory access happens to ses_dev->page10 which has a
> size of 1200 bytes in this case. The invalid memory access happens in:
>
> 600 if (addl_desc_ptr &&
> 601 /* only find additional descriptions for specific devices */
> 602 (type_ptr[0] == ENCLOSURE_COMPONENT_DEVICE ||
> 603 type_ptr[0] == ENCLOSURE_COMPONENT_ARRAY_DEVICE ||
> 604 type_ptr[0] == ENCLOSURE_COMPONENT_SAS_EXPANDER ||
> 605 /* these elements are optional */
> 606 type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_TARGET_PORT ||
> 607 type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_INITIATOR_PORT ||
> 608 type_ptr[0] == ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS))
> 609 addl_desc_ptr += addl_desc_ptr[1] + 2; <-- here
>
> To fix the out-of-bounds memory access, code is now added to make sure
> that addl_desc_ptr will never point to an address outside of its bounds.
>
> With this patch, the KASAN warning is gone.
>
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
> ---
> drivers/scsi/ses.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
> index 0fc39224ce1e..dbc9acc2df2f 100644
> --- a/drivers/scsi/ses.c
> +++ b/drivers/scsi/ses.c
> @@ -605,9 +605,14 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
> /* these elements are optional */
> type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_TARGET_PORT ||
> type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_INITIATOR_PORT ||
> - type_ptr[0] == ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS))
> + type_ptr[0] == ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS)) {
> addl_desc_ptr += addl_desc_ptr[1] + 2;
>
> + /* Ensure no out-of-bounds memory access */
> + if (addl_desc_ptr >= ses_dev->page10 +
> + ses_dev->page10_len)
> + addl_desc_ptr = NULL;
> + }
> }
> }
> kfree(buf);

Ping! Any comment on this patch.

Cheers,
Longman