nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells
If a cell has 'nbits' equal to a multiple of BITS_PER_BYTE the logic
*p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
will become undefined behavior because nbits modulo BITS_PER_BYTE is 0, and we
subtract one from that making a large number that is then shifted more than the
number of bits that fit into an unsigned long.
UBSAN reports this problem:
UBSAN: shift-out-of-bounds in drivers/nvmem/core.c:1386:8
shift exponent 64 is too large for 64-bit type 'unsigned long'
CPU: 6 PID: 7 Comm: kworker/u16:0 Not tainted 5.15.0-rc3+ #9
Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
Workqueue: events_unbound deferred_probe_work_func
Call trace:
dump_backtrace+0x0/0x170
show_stack+0x24/0x30
dump_stack_lvl+0x64/0x7c
dump_stack+0x18/0x38
ubsan_epilogue+0x10/0x54
__ubsan_handle_shift_out_of_bounds+0x180/0x194
__nvmem_cell_read+0x1ec/0x21c
nvmem_cell_read+0x58/0x94
nvmem_cell_read_variable_common+0x4c/0xb0
nvmem_cell_read_variable_le_u32+0x40/0x100
a6xx_gpu_init+0x170/0x2f4
adreno_bind+0x174/0x284
component_bind_all+0xf0/0x264
msm_drm_bind+0x1d8/0x7a0
try_to_bring_up_master+0x164/0x1ac
__component_add+0xbc/0x13c
component_add+0x20/0x2c
dp_display_probe+0x340/0x384
platform_probe+0xc0/0x100
really_probe+0x110/0x304
__driver_probe_device+0xb8/0x120
driver_probe_device+0x4c/0xfc
__device_attach_driver+0xb0/0x128
bus_for_each_drv+0x90/0xdc
__device_attach+0xc8/0x174
device_initial_probe+0x20/0x2c
bus_probe_device+0x40/0xa4
deferred_probe_work_func+0x7c/0xb8
process_one_work+0x128/0x21c
process_scheduled_works+0x40/0x54
worker_thread+0x1ec/0x2a8
kthread+0x138/0x158
ret_from_fork+0x10/0x20
Fix it by making sure there are any bits to mask out.
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Solution
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Workaround
No workaround given by the vendor.
Wed, 24 Sep 2025 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-787 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:* |
|
| Vendors & Products |
Linux
Linux linux Kernel |
|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Mon, 10 Mar 2025 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat rhel Eus
|
|
| CPEs | cpe:/a:redhat:rhel_eus:9.4 | |
| Vendors & Products |
Redhat rhel Eus
|
Wed, 13 Nov 2024 02:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9 |
Mon, 04 Nov 2024 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Tue, 24 Sep 2024 11:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:/o:redhat:enterprise_linux:8 |
Tue, 24 Sep 2024 06:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat enterprise Linux |
|
| CPEs | cpe:/a:redhat:enterprise_linux:8::nfv | |
| Vendors & Products |
Redhat
Redhat enterprise Linux |
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-04T07:12:19.190Z
Reserved: 2024-05-22T06:20:56.203Z
Link: CVE-2021-47497
Updated: 2024-08-04T05:39:59.611Z
Status : Analyzed
Published: 2024-05-22T09:15:11.513
Modified: 2025-09-24T19:16:48.953
Link: CVE-2021-47497
OpenCVE Enrichment
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