bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge
3Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackepss 0.2%
exploitation probability
0.2%top 96% of all CVEs
observed exploitation
nono source reports it
In the Linux kernel, the following vulnerability has been resolved:
bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge
Nicholas Carlini reported a bug in precision backtracking mechanism
for BPF_LD | BPF_{IND,ABS} instructions. These instructions are
modelled as two branches:
- fallthrough;
- implicit exit from current subprogram.
The implicit exit case was not handled by the backtrack_insn()
function. When backtracking such a path backtrack_insn() did not
call bt_subprog_enter(), which meant that backtracking continued
manipulating precision marks in a caller frame, while looking at
instructions in a callee frame.
This lead to segmentation faults during verification (see the
selftest), or unsound state pruning.
Affected products
Linux · Linux