7.8
/ 10
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Description
In the Linux kernel, the following vulnerability has been resolved:
bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.
Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.
This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
64-bit loads/stores are only guaranteed to be single-copy atomic if
they are 64-bit aligned. A misaligned target risks a torn read,
causing the JIT to jump to a corrupted address.
Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.
bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.
Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.
This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
64-bit loads/stores are only guaranteed to be single-copy atomic if
they are 64-bit aligned. A misaligned target risks a torn read,
causing the JIT to jump to a corrupted address.
Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.
Basic Information
ID
CVE-2026-23383
Source
Linux
Published
Mar 25, 2026 at 10:28
Modified
Apr 2, 2026 at 14:44
Affected Product
Vendor
Linux
Product
Linux
Version
b2ad54e1533e91449cb2a371e034942bd7882b58
Affected Versions
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux 6.0
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux b2ad54e1533e91449cb2a371e034942bd7882b58
Linux Linux 6.0