CVE-2021-47497: nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells
First published: Wed May 22 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: 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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/kernel | <4.4.290 | 4.4.290 |
| redhat/kernel | <4.9.288 | 4.9.288 |
| redhat/kernel | <4.14.252 | 4.14.252 |
| redhat/kernel | <4.19.213 | 4.19.213 |
| redhat/kernel | <5.4.155 | 5.4.155 |
| redhat/kernel | <5.10.75 | 5.10.75 |
| redhat/kernel | <5.14.14 | 5.14.14 |
| redhat/kernel | <5.15 | 5.15 |
| IBM Security Verify Governance - Identity Manager | <=ISVG 10.0.2 | |
| IBM Security Verify Governance, Identity Manager Software Stack | <=ISVG 10.0.2 | |
| IBM Security Verify Governance, Identity Manager Virtual Appliance | <=ISVG 10.0.2 | |
| IBM Security Verify Governance Identity Manager Container | <=ISVG 10.0.2 |
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Reference Links
- https://git.kernel.org/stable/c/0594f1d048d8dc338eb9a240021b1d00ae1eb082
- https://git.kernel.org/stable/c/0e822e5413da1af28cca350cb1cb42b6133bdcae
- https://git.kernel.org/stable/c/2df6c023050205c4d04ffc121bc549f65cb8d1df
- https://git.kernel.org/stable/c/57e48886401b14cd351423fabfec2cfd18df4f66
- https://git.kernel.org/stable/c/5d388fa01fa6eb310ac023a363a6cb216d9d8fe9
- https://git.kernel.org/stable/c/60df06bbdf497e37ed25ad40572c362e5b0998df
- https://git.kernel.org/stable/c/abcb8d33e4d2215ccde5ab5ccf9f730a59d79d97
- https://git.kernel.org/stable/c/eb0fc8e7170e61eaf65d28dee4a8baf4e86b19ca
- https://access.redhat.com/security/cve/CVE-2021-47497
- https://lore.kernel.org/linux-cve-announce/2024052242-CVE-2021-47497-449e@gregkh/T
- https://access.redhat.com/errata/RHSA-2024:7001
- https://access.redhat.com/errata/RHSA-2024:7000
- https://access.redhat.com/errata/RHSA-2024:9315
- https://access.redhat.com/errata/RHSA-2025:2490
- https://bugzilla.redhat.com/show_bug.cgi?id=2282918
- https://www.ibm.com/support/pages/node/7230443 (Advisory)
Frequently Asked Questions
What is the severity of CVE-2021-47497?
CVE-2021-47497 has not been assigned a specific severity rating but involves a potential undefined behavior due to a shift-out-of-bounds issue.
How do I fix CVE-2021-47497?
To fix CVE-2021-47497, upgrade to the kernel versions 4.4.290, 4.9.288, 4.14.252, 4.19.213, 5.4.155, 5.10.75, 5.14.14, or 5.15.
What systems are affected by CVE-2021-47497?
CVE-2021-47497 affects certain versions of the Linux kernel, specifically those prior to the listed remedial versions.
Is CVE-2021-47497 exploitable in the wild?
There is currently no public information indicating that CVE-2021-47497 is actively exploited in the wild.
What are the potential impacts of CVE-2021-47497?
The potential impacts of CVE-2021-47497 include system instability or crashes due to undefined behavior in the kernel.
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