| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
ALSA: mts64: fix possible null-ptr-defer in snd_mts64_interrupt
I got a null-ptr-defer error report when I do the following tests
on the qemu platform:
make defconfig and CONFIG_PARPORT=m, CONFIG_PARPORT_PC=m,
CONFIG_SND_MTS64=m
Then making test scripts:
cat>test_mod1.sh<<EOF
modprobe snd-mts64
modprobe snd-mts64
EOF
Executing the script, perhaps several times, we will get a null-ptr-defer
report, as follow:
syzkaller:~# ./test_mod.sh
snd_mts64: probe of snd_mts64.0 failed with error -5
modprobe: ERROR: could not insert 'snd_mts64': No such device
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 0 PID: 205 Comm: modprobe Not tainted 6.1.0-rc8-00588-g76dcd734eca2 #6
Call Trace:
<IRQ>
snd_mts64_interrupt+0x24/0xa0 [snd_mts64]
parport_irq_handler+0x37/0x50 [parport]
__handle_irq_event_percpu+0x39/0x190
handle_irq_event_percpu+0xa/0x30
handle_irq_event+0x2f/0x50
handle_edge_irq+0x99/0x1b0
__common_interrupt+0x5d/0x100
common_interrupt+0xa0/0xc0
</IRQ>
<TASK>
asm_common_interrupt+0x22/0x40
RIP: 0010:_raw_write_unlock_irqrestore+0x11/0x30
parport_claim+0xbd/0x230 [parport]
snd_mts64_probe+0x14a/0x465 [snd_mts64]
platform_probe+0x3f/0xa0
really_probe+0x129/0x2c0
__driver_probe_device+0x6d/0xc0
driver_probe_device+0x1a/0xa0
__device_attach_driver+0x7a/0xb0
bus_for_each_drv+0x62/0xb0
__device_attach+0xe4/0x180
bus_probe_device+0x82/0xa0
device_add+0x550/0x920
platform_device_add+0x106/0x220
snd_mts64_attach+0x2e/0x80 [snd_mts64]
port_check+0x14/0x20 [parport]
bus_for_each_dev+0x6e/0xc0
__parport_register_driver+0x7c/0xb0 [parport]
snd_mts64_module_init+0x31/0x1000 [snd_mts64]
do_one_initcall+0x3c/0x1f0
do_init_module+0x46/0x1c6
load_module+0x1d8d/0x1e10
__do_sys_finit_module+0xa2/0xf0
do_syscall_64+0x37/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
</TASK>
Kernel panic - not syncing: Fatal exception in interrupt
Rebooting in 1 seconds..
The mts wa not initialized during interrupt, we add check for
mts to fix this bug. |
| In the Linux kernel, the following vulnerability has been resolved:
media: uvcvideo: Fix memory leak in uvc_gpio_parse
Previously the unit buffer was allocated before checking the IRQ for
privacy GPIO. In case of error, the unit buffer was leaked.
Allocate the unit buffer after the IRQ to avoid it.
Addresses-Coverity-ID: 1474639 ("Resource leak") |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: Fix use-after-free in ath9k_hif_usb_disconnect()
This patch fixes a use-after-free in ath9k that occurs in
ath9k_hif_usb_disconnect() when ath9k_destroy_wmi() is trying to access
'drv_priv' that has already been freed by ieee80211_free_hw(), called by
ath9k_htc_hw_deinit(). The patch moves ath9k_destroy_wmi() before
ieee80211_free_hw(). Note that urbs from the driver should be killed
before freeing 'wmi' with ath9k_destroy_wmi() as their callbacks will
access 'wmi'.
Found by a modified version of syzkaller.
==================================================================
BUG: KASAN: use-after-free in ath9k_destroy_wmi+0x38/0x40
Read of size 8 at addr ffff8881069132a0 by task kworker/0:1/7
CPU: 0 PID: 7 Comm: kworker/0:1 Tainted: G O 5.14.0+ #131
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
Workqueue: usb_hub_wq hub_event
Call Trace:
dump_stack_lvl+0x8e/0xd1
print_address_description.constprop.0.cold+0x93/0x334
? ath9k_destroy_wmi+0x38/0x40
? ath9k_destroy_wmi+0x38/0x40
kasan_report.cold+0x83/0xdf
? ath9k_destroy_wmi+0x38/0x40
ath9k_destroy_wmi+0x38/0x40
ath9k_hif_usb_disconnect+0x329/0x3f0
? ath9k_hif_usb_suspend+0x120/0x120
? usb_disable_interface+0xfc/0x180
usb_unbind_interface+0x19b/0x7e0
? usb_autoresume_device+0x50/0x50
device_release_driver_internal+0x44d/0x520
bus_remove_device+0x2e5/0x5a0
device_del+0x5b2/0xe30
? __device_link_del+0x370/0x370
? usb_remove_ep_devs+0x43/0x80
? remove_intf_ep_devs+0x112/0x1a0
usb_disable_device+0x1e3/0x5a0
usb_disconnect+0x267/0x870
hub_event+0x168d/0x3950
? rcu_read_lock_sched_held+0xa1/0xd0
? hub_port_debounce+0x2e0/0x2e0
? check_irq_usage+0x860/0xf20
? drain_workqueue+0x281/0x360
? lock_release+0x640/0x640
? rcu_read_lock_sched_held+0xa1/0xd0
? rcu_read_lock_bh_held+0xb0/0xb0
? lockdep_hardirqs_on_prepare+0x273/0x3e0
process_one_work+0x92b/0x1460
? pwq_dec_nr_in_flight+0x330/0x330
? rwlock_bug.part.0+0x90/0x90
worker_thread+0x95/0xe00
? __kthread_parkme+0x115/0x1e0
? process_one_work+0x1460/0x1460
kthread+0x3a1/0x480
? set_kthread_struct+0x120/0x120
ret_from_fork+0x1f/0x30
The buggy address belongs to the page:
page:ffffea00041a44c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x106913
flags: 0x200000000000000(node=0|zone=2)
raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), pid 7, ts 38347963444, free_ts 41399957635
prep_new_page+0x1aa/0x240
get_page_from_freelist+0x159a/0x27c0
__alloc_pages+0x2da/0x6a0
alloc_pages+0xec/0x1e0
kmalloc_order+0x39/0xf0
kmalloc_order_trace+0x19/0x120
__kmalloc+0x308/0x390
wiphy_new_nm+0x6f5/0x1dd0
ieee80211_alloc_hw_nm+0x36d/0x2230
ath9k_htc_probe_device+0x9d/0x1e10
ath9k_htc_hw_init+0x34/0x50
ath9k_hif_usb_firmware_cb+0x25f/0x4e0
request_firmware_work_func+0x131/0x240
process_one_work+0x92b/0x1460
worker_thread+0x95/0xe00
kthread+0x3a1/0x480
page last free stack trace:
free_pcp_prepare+0x3d3/0x7f0
free_unref_page+0x1e/0x3d0
device_release+0xa4/0x240
kobject_put+0x186/0x4c0
put_device+0x20/0x30
ath9k_htc_disconnect_device+0x1cf/0x2c0
ath9k_htc_hw_deinit+0x26/0x30
ath9k_hif_usb_disconnect+0x2d9/0x3f0
usb_unbind_interface+0x19b/0x7e0
device_release_driver_internal+0x44d/0x520
bus_remove_device+0x2e5/0x5a0
device_del+0x5b2/0xe30
usb_disable_device+0x1e3/0x5a0
usb_disconnect+0x267/0x870
hub_event+0x168d/0x3950
process_one_work+0x92b/0x1460
Memory state around the buggy address:
ffff888106913180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888106913200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_cake: Fix incorrect qlen reduction in cake_drop
In cake_drop(), qdisc_tree_reduce_backlog() is used to update the qlen
and backlog of the qdisc hierarchy. Its caller, cake_enqueue(), assumes
that the parent qdisc will enqueue the current packet. However, this
assumption breaks when cake_enqueue() returns NET_XMIT_CN: the parent
qdisc stops enqueuing current packet, leaving the tree qlen/backlog
accounting inconsistent. This mismatch can lead to a NULL dereference
(e.g., when the parent Qdisc is qfq_qdisc).
This patch computes the qlen/backlog delta in a more robust way by
observing the difference before and after the series of cake_drop()
calls, and then compensates the qdisc tree accounting if cake_enqueue()
returns NET_XMIT_CN.
To ensure correct compensation when ACK thinning is enabled, a new
variable is introduced to keep qlen unchanged. |
| In the Linux kernel, the following vulnerability has been resolved:
gpu: lontium-lt9611: Fix NULL pointer dereference in lt9611_connector_init()
A NULL check for bridge->encoder shows that it may be NULL, but it
already been dereferenced on all paths leading to the check.
812 if (!bridge->encoder) {
Dereference the pointer bridge->encoder.
810 drm_connector_attach_encoder(<9611->connector, bridge->encoder); |
| In the Linux kernel, the following vulnerability has been resolved:
usb: typec: ucsi: fix use-after-free caused by uec->work
The delayed work uec->work is scheduled in gaokun_ucsi_probe()
but never properly canceled in gaokun_ucsi_remove(). This creates
use-after-free scenarios where the ucsi and gaokun_ucsi structure
are freed after ucsi_destroy() completes execution, while the
gaokun_ucsi_register_worker() might be either currently executing
or still pending in the work queue. The already-freed gaokun_ucsi
or ucsi structure may then be accessed.
Furthermore, the race window is 3 seconds, which is sufficiently
long to make this bug easily reproducible. The following is the
trace captured by KASAN:
==================================================================
BUG: KASAN: slab-use-after-free in __run_timers+0x5ec/0x630
Write of size 8 at addr ffff00000ec28cc8 by task swapper/0/0
...
Call trace:
show_stack+0x18/0x24 (C)
dump_stack_lvl+0x78/0x90
print_report+0x114/0x580
kasan_report+0xa4/0xf0
__asan_report_store8_noabort+0x20/0x2c
__run_timers+0x5ec/0x630
run_timer_softirq+0xe8/0x1cc
handle_softirqs+0x294/0x720
__do_softirq+0x14/0x20
____do_softirq+0x10/0x1c
call_on_irq_stack+0x30/0x48
do_softirq_own_stack+0x1c/0x28
__irq_exit_rcu+0x27c/0x364
irq_exit_rcu+0x10/0x1c
el1_interrupt+0x40/0x60
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x6c/0x70
arch_local_irq_enable+0x4/0x8 (P)
do_idle+0x334/0x458
cpu_startup_entry+0x60/0x70
rest_init+0x158/0x174
start_kernel+0x2f8/0x394
__primary_switched+0x8c/0x94
Allocated by task 72 on cpu 0 at 27.510341s:
kasan_save_stack+0x2c/0x54
kasan_save_track+0x24/0x5c
kasan_save_alloc_info+0x40/0x54
__kasan_kmalloc+0xa0/0xb8
__kmalloc_node_track_caller_noprof+0x1c0/0x588
devm_kmalloc+0x7c/0x1c8
gaokun_ucsi_probe+0xa0/0x840 auxiliary_bus_probe+0x94/0xf8
really_probe+0x17c/0x5b8
__driver_probe_device+0x158/0x2c4
driver_probe_device+0x10c/0x264
__device_attach_driver+0x168/0x2d0
bus_for_each_drv+0x100/0x188
__device_attach+0x174/0x368
device_initial_probe+0x14/0x20
bus_probe_device+0x120/0x150
device_add+0xb3c/0x10fc
__auxiliary_device_add+0x88/0x130
...
Freed by task 73 on cpu 1 at 28.910627s:
kasan_save_stack+0x2c/0x54
kasan_save_track+0x24/0x5c
__kasan_save_free_info+0x4c/0x74
__kasan_slab_free+0x60/0x8c
kfree+0xd4/0x410
devres_release_all+0x140/0x1f0
device_unbind_cleanup+0x20/0x190
device_release_driver_internal+0x344/0x460
device_release_driver+0x18/0x24
bus_remove_device+0x198/0x274
device_del+0x310/0xa84
...
The buggy address belongs to the object at ffff00000ec28c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 200 bytes inside of
freed 512-byte region
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4ec28
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x3fffe0000000040(head|node=0|zone=0|lastcpupid=0x1ffff)
page_type: f5(slab)
raw: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 03fffe0000000002 fffffdffc03b0a01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff00000ec28b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff00000ec28c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff00000ec28c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff00000ec28d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff00000ec28d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
================================================================
---truncated--- |
| The VAPIX Edge storage API that allowed a privilege escalation, enabling a VAPIX administrator-privileged user to gain Linux Root privileges. This flaw can only be exploited after authenticating with an administrator-privileged service account. |
| In the Linux kernel, the following vulnerability has been resolved:
objtool: Fix SEGFAULT
find_insn() will return NULL in case of failure. Check insn in order
to avoid a kernel Oops for NULL pointer dereference. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()
It is possible that skb is freed in ath9k_htc_rx_msg(), then
usb_submit_urb() fails and we try to free skb again. It causes
use-after-free bug. Moreover, if alloc_skb() fails, urb->context becomes
NULL but rx_buf is not freed and there can be a memory leak.
The patch removes unnecessary nskb and makes skb processing more clear: it
is supposed that ath9k_htc_rx_msg() either frees old skb or passes its
managing to another callback function.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller. |
| A local privilege-escalation vulnerability has been discovered in the HPE Aruba Networking Virtual Intranet Access (VIA) client. Successful exploitation of this vulnerability could allow a local attacker to achieve arbitrary code execution with root privileges. |
| In the Linux kernel, the following vulnerability has been resolved:
soc: mediatek: mtk-svs: Enable the IRQ later
If the system does not come from reset (like when is booted via
kexec()), the peripheral might triger an IRQ before the data structures
are initialised.
[ 0.227710] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000f08
[ 0.227913] Call trace:
[ 0.227918] svs_isr+0x8c/0x538 |
| In the Linux kernel, the following vulnerability has been resolved:
md: raid1: fix potential OOB in raid1_remove_disk()
If rddev->raid_disk is greater than mddev->raid_disks, there will be
an out-of-bounds in raid1_remove_disk(). We have already found
similar reports as follows:
1) commit d17f744e883b ("md-raid10: fix KASAN warning")
2) commit 1ebc2cec0b7d ("dm raid: fix KASAN warning in raid5_remove_disk")
Fix this bug by checking whether the "number" variable is
valid. |
| In the Linux kernel, the following vulnerability has been resolved:
phy: stm32-usphyc: Fix off by one in probe()
The "index" variable is used as an index into the usbphyc->phys[] array
which has usbphyc->nphys elements. So if it is equal to usbphyc->nphys
then it is one element out of bounds. The "index" comes from the
device tree so it's data that we trust and it's unlikely to be wrong,
however it's obviously still worth fixing the bug. Change the > to >=. |
| In the Linux kernel, the following vulnerability has been resolved:
pstore: Avoid kcore oops by vmap()ing with VM_IOREMAP
An oops can be induced by running 'cat /proc/kcore > /dev/null' on
devices using pstore with the ram backend because kmap_atomic() assumes
lowmem pages are accessible with __va().
Unable to handle kernel paging request at virtual address ffffff807ff2b000
Mem abort info:
ESR = 0x96000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000081d87000
[ffffff807ff2b000] pgd=180000017fe18003, p4d=180000017fe18003, pud=180000017fe18003, pmd=0000000000000000
Internal error: Oops: 96000006 [#1] PREEMPT SMP
Modules linked in: dm_integrity
CPU: 7 PID: 21179 Comm: perf Not tainted 5.15.67-10882-ge4eb2eb988cd #1 baa443fb8e8477896a370b31a821eb2009f9bfba
Hardware name: Google Lazor (rev3 - 8) (DT)
pstate: a0400009 (NzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __memcpy+0x110/0x260
lr : vread+0x194/0x294
sp : ffffffc013ee39d0
x29: ffffffc013ee39f0 x28: 0000000000001000 x27: ffffff807ff2b000
x26: 0000000000001000 x25: ffffffc0085a2000 x24: ffffff802d4b3000
x23: ffffff80f8a60000 x22: ffffff802d4b3000 x21: ffffffc0085a2000
x20: ffffff8080b7bc68 x19: 0000000000001000 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: ffffffd3073f2e60
x14: ffffffffad588000 x13: 0000000000000000 x12: 0000000000000001
x11: 00000000000001a2 x10: 00680000fff2bf0b x9 : 03fffffff807ff2b
x8 : 0000000000000001 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffffff802d4b4000 x4 : ffffff807ff2c000 x3 : ffffffc013ee3a78
x2 : 0000000000001000 x1 : ffffff807ff2b000 x0 : ffffff802d4b3000
Call trace:
__memcpy+0x110/0x260
read_kcore+0x584/0x778
proc_reg_read+0xb4/0xe4
During early boot, memblock reserves the pages for the ramoops reserved
memory node in DT that would otherwise be part of the direct lowmem
mapping. Pstore's ram backend reuses those reserved pages to change the
memory type (writeback or non-cached) by passing the pages to vmap()
(see pfn_to_page() usage in persistent_ram_vmap() for more details) with
specific flags. When read_kcore() starts iterating over the vmalloc
region, it runs over the virtual address that vmap() returned for
ramoops. In aligned_vread() the virtual address is passed to
vmalloc_to_page() which returns the page struct for the reserved lowmem
area. That lowmem page is passed to kmap_atomic(), which effectively
calls page_to_virt() that assumes a lowmem page struct must be directly
accessible with __va() and friends. These pages are mapped via vmap()
though, and the lowmem mapping was never made, so accessing them via the
lowmem virtual address oopses like above.
Let's side-step this problem by passing VM_IOREMAP to vmap(). This will
tell vread() to not include the ramoops region in the kcore. Instead the
area will look like a bunch of zeros. The alternative is to teach kmap()
about vmalloc areas that intersect with lowmem. Presumably such a change
isn't a one-liner, and there isn't much interest in inspecting the
ramoops region in kcore files anyway, so the most expedient route is
taken for now. |
| In the Linux kernel, the following vulnerability has been resolved:
block: fix blktrace debugfs entries leakage
Commit 99d055b4fd4b ("block: remove per-disk debugfs files in
blk_unregister_queue") moves blk_trace_shutdown() from
blk_release_queue() to blk_unregister_queue(), this is safe if blktrace
is created through sysfs, however, there is a regression in corner
case.
blktrace can still be enabled after del_gendisk() through ioctl if
the disk is opened before del_gendisk(), and if blktrace is not shutdown
through ioctl before closing the disk, debugfs entries will be leaked.
Fix this problem by shutdown blktrace in disk_release(), this is safe
because blk_trace_remove() is reentrant. |
| In the Linux kernel, the following vulnerability has been resolved:
driver: soc: xilinx: use _safe loop iterator to avoid a use after free
The hash_for_each_possible() loop dereferences "eve_data" to get the
next item on the list. However the loop frees eve_data so it leads to
a use after free. Use hash_for_each_possible_safe() instead. |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: fix potential memory leak in mlx5e_init_rep_rx
The memory pointed to by the priv->rx_res pointer is not freed in the error
path of mlx5e_init_rep_rx, which can lead to a memory leak. Fix by freeing
the memory in the error path, thereby making the error path identical to
mlx5e_cleanup_rep_rx(). |
| In the Linux kernel, the following vulnerability has been resolved:
hte: tegra-194: Fix off by one in tegra_hte_map_to_line_id()
The "map_sz" is the number of elements in the "m" array so the >
comparison needs to be changed to >= to prevent an out of bounds
read. |
| In the Linux kernel, the following vulnerability has been resolved:
remoteproc: qcom: pas: Shutdown lite ADSP DTB on X1E
The ADSP firmware on X1E has separate firmware binaries for the main
firmware and the DTB. The same applies for the "lite" firmware loaded by
the boot firmware.
When preparing to load the new ADSP firmware we shutdown the lite_pas_id
for the main firmware, but we don't shutdown the corresponding lite pas_id
for the DTB. The fact that we're leaving it "running" forever becomes
obvious if you try to reuse (or just access) the memory region used by the
"lite" firmware: The &adsp_boot_mem is accessible, but accessing the
&adsp_boot_dtb_mem results in a crash.
We don't support reusing the memory regions currently, but nevertheless we
should not keep part of the lite firmware running. Fix this by adding the
lite_dtb_pas_id and shutting it down as well.
We don't have a way to detect if the lite firmware is actually running yet,
so ignore the return status of qcom_scm_pas_shutdown() for now. This was
already the case before, the assignment to "ret" is not used anywhere. |
| In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix shift-out-of-bounds due to too large exponent of block size
If field s_log_block_size of superblock data is corrupted and too large,
init_nilfs() and load_nilfs() still can trigger a shift-out-of-bounds
warning followed by a kernel panic (if panic_on_warn is set):
shift exponent 38973 is too large for 32-bit type 'int'
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
ubsan_epilogue+0xb/0x50
__ubsan_handle_shift_out_of_bounds.cold.12+0x17b/0x1f5
init_nilfs.cold.11+0x18/0x1d [nilfs2]
nilfs_mount+0x9b5/0x12b0 [nilfs2]
...
This fixes the issue by adding and using a new helper function for getting
block size with sanity check. |
