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CVE-2026-98043

bpf: Don't infer non-NULL from a pointer with an unbounded offset PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: bpf: Don't infer non-NULL from a pointer with an unbounded offset reg_not_null() decides that a register holds a non-NULL value by looking at its type alone. For pointer types that allow arithmetic the type only guarantees a non-NULL base, in case of an unbound offset the runtime offset value might still add up to NULL. Consider the followng program: r6 = bpf_map_lookup_elem(map, &0); /* present */ if (r6 == 0) return 0; r7 = bpf_map_lookup_elem(map, &1); /* absent, NULL at runtime */ r8 = r7; r8 -= r6; /* pointer - pointer: unknown scalar, -r6 */ r8 <<= 1; r8 >>= 1; /* any non-negative offset is accepted by */ /* check_reg_sane_offset_ptr() */ r6 += r8; /* verifier: map value; runtime: zero */ if (r7 != r6) return 0; *(u8 *)(r7 + 0); /* r7 is inferred non-NULL, both are zero */ At runtime both registers are zero, the comparison is true and the load faults with NULL pointer dereference. Require the offset to be within +-BPF_MAX_VAR_OFF in reg_not_null().

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected cac616db39c207dc63465a4e05c6ce0e60b2cce4 before 8b414dbe97fcefd116e5a620c3bd9993014aa4ce; affected cac616db39c207dc63465a4e05c6ce0e60b2cce4 before 019d845a08b8ccfe8eefaaf4bca6870f2b8c58ae; affected cac616db39c207dc63465a4e05c6ce0e60b2cce4 before 65bea674f43c09c0eda033a140dfac6a2842a19f; affected cac616db39c207dc63465a4e05c6ce0e60b2cce4 before cb6642048739bf4ee5aa09fe465511f1e87caa63; affected cac616db39c207dc63465a4e05c6ce0e60b2cce4 before 67b529f521a6676cdfc78b91b0217d7eaa84216b
Linux / Linuxaffected 5.8; unaffected 0 before 5.8; unaffected 6.6.160 through 6.6.*; unaffected 6.12.114 through 6.12.*; unaffected 6.18.57 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References