# CVE-2021-47463: linux: In the Linux kernel, the following vulnerability has been resolved:  mm/secretmem: fix NULL page->mapping dereference...

CVE-2021-47463 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47463, released May 22, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47463
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 22, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  mm/secretmem: fix NULL page->mapping dereference in page_is_secretmem()  Check for a NULL page->mapping before dereferencing the mapping in page_is_secretmem(), as the page's mapping can be nullified while gup() is running, e.g.  by reclaim or truncation.    BUG: kernel NULL pointer dereference, address: 0000000000000068   #PF: supervisor read access in kernel mode   #PF: error_code(0x0000) - not-present page   PGD 0 P4D 0   Oops: 0000 [#1] PREEMPT SMP NOPTI   CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G        W   RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0   Code: <48> 81 7a 68 80 08 04 bc 0f 85 21 ff ff 8 89 c7 be   RSP: 0018:ffffaa90087679b0 EFLAGS: 00010046   RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934   RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900   ...   CR2: 0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0   Call Trace:    get_user_pages_fast_only+0x13/0x20    hva_to_pfn+0xa9/0x3e0    try_async_pf+0xa1/0x270    direct_page_fault+0x113/0xad0    kvm_mmu_page_fault+0x69/0x680    vmx_handle_exit+0xe1/0x5d0    kvm_arch_vcpu_ioctl_run+0xd81/0x1c70    kvm_vcpu_ioctl+0x267/0x670    __x64_sys_ioctl+0x83/0xa0    do_syscall_64+0x56/0x80    entry_SYSCALL_64_after_hwframe+0x44/0xae

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.16-1 | [DEBIAN-CVE-2021-47463](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47463.md) | May 22, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.16-1 | [DEBIAN-CVE-2021-47463](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47463.md) | May 22, 2024 |
| Linux | linux Debian 14 | 5.14.16-1 | [DEBIAN-CVE-2021-47463](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47463.md) | May 22, 2024 |

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