bpf: account for current allocated stack depth in widen_imprecise_scalars()

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: account for current allocated stack depth in widen_imprecise_scalars() The usage pattern for widen_imprecise_scalars() looks as follows: prev_st = find_prev_entry(env, ...); queued_st = push_stack(...); widen_imprecise_scalars(env, prev_st, queued_st); Where prev_st is an ancestor of the queued_st in the explored states tree. This ancestor is not guaranteed to have same allocated stack depth as queued_st. E.g. in the following case: def main(): for i in 1..2: foo(i) // same callsite, differnt param def foo(i): if i == 1: use 128 bytes of stack iterator based loop Here, for a second 'foo' call prev_st->allocated_stack is 128, while queued_st->allocated_stack is much smaller. widen_imprecise_scalars() needs to take this into account and avoid accessing bpf_verifier_state->frame[*]->stack out of bounds.

Timeline

1. Dec 16, 2025, 1:48 PM UTCCVE published
2. Oct 15, 2026, 10:00 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 15, 2026, 10:02 PM UTCRecord last updated

Affected versions

• Linux Linux

  From ab470fefce2837e66b771c60858118d50bb5bb10 · fixed in 64b12dca2b0abcb5fc0542887d18b926ea5cf711; From 2793a8b015f7f1caadb9bce9c63dc659f7522676 · fixed in 9944c7938cd5b3f37b0afec0481c7c015e4f1c58; From 2793a8b015f7f1caadb9bce9c63dc659f7522676 · fixed in 57e04e2ff56e32f923154f0f7bc476fcb596ffe7; From 2793a8b015f7f1caadb9bce9c63dc659f7522676 · fixed in b0c8e6d3d866b6a7f73877f71968dbffd27b7785; From 6.6.15 · fixed in 6.6.117

• Linux Linux

  6.7

• KernelLinux

  fixed in 6.6.117; From 6.7.0 · fixed in 6.12.59; fixed in 6.17.9

References 4