Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject legacy packet loads from callbacks check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a subprogram as an implicit return with R0 set to zero. It calls prepare_func_exit() to explore this synthesized path. When the load is reached directly from a synchronous callback, prepare_func_exit() enforces the callback return contract and marks R0 precise. R0 is not derived from a real instruction on this path, so precision backtracking reaches the callback call with R0 still requested and triggers the "callback unexpected regs" verifier bug. A privileged program loader can therefore cause a verifier warning and an -EFAULT BPF_PROG_LOAD. These legacy packet-load instructions are deprecated. Reject them from callbacks rather than complicating their implicit-return model. Check all active frames before constructing the implicit return so nested static subprograms cannot hide the callback context. Global functions are verified independently with a fresh frame zero, so an active-frame check cannot identify a global function called from a callback. Also check the complete subprogram call graph during stack-depth validation and reject a function containing a legacy load when any caller is a callback. This covers global and static descendants without making has_ld_abs transitive, preserving its per-function BTF return-type check. Ordinary uses outside callbacks remain supported.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 8674e2db06cff6b50f2216eed9a761d15425bb34 before cebda2a2bb4183550eae9dcf888c16407b4fffda; affected ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337 before 3484a99303912db62428494a9061212049027e57; affected ee861486e377edc55361c08dcbceab3f6b6577bd before bc489c0c9b8c86bd7fac42cfd1bb152f042fca56; affected ee861486e377edc55361c08dcbceab3f6b6577bd before e7d28823c662128caae63f14e16bd394916c139b; affected 928d354ae3557e8f755a227e67be88034eb3cd7f; affected 8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe; affected de1055e7f9e67af32b1f3376066272b04e5223c0; affected 37ad2bb11e9de92cb7b94548705eeedd87f7d392; affected d846d83bdacbd8f14fc45c63b8c1d22608452e1c; affected 6.12.101 before 6.12.114; affected 6.18.42 before 6.18.53; affected 5.10.265 before 5.11; affected 5.15.216 before 5.16; affected 6.1.183 before 6.2; affected 6.6.148 before 6.7; affected 7.0.10 before 7.1 |
| Linux / Linux | affected 7.1; unaffected 0 before 7.1; unaffected 6.12.114 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.