linux-stable.git/kernel/bpf/states.c, branch linux-rolling-stable Linux kernel stable tree bpf: Preserve pointer spill metadata during half-slot cleanup 2026-07-24T14:20:24+00:00 Nuoqi Gui gnq25@mails.tsinghua.edu.cn 2026-06-17T15:20:20+00:00 0f9278b22cda6fd2525049930157b79b4036b4ef [ Upstream commit 3a354149bceacadbcf7d7b4766f5ef26a85892ab ] __clean_func_state() cleans dead stack slots in 4-byte halves. When the high half of a STACK_SPILL slot is dead and the low half remains live, cleanup converts the live low half to STACK_MISC or STACK_ZERO and clears the saved spilled_ptr metadata. That conversion is safe only for scalar spills. For a pointer spill, this metadata clear lets a later 32-bit fill from the still-live half avoid the normal non-scalar register-fill check and be treated as an ordinary scalar stack read. Leave non-scalar spill slots intact in this half-live shape. This is conservative for pruning and preserves the existing check_stack_read_fixed_off() rejection path for partial fills from pointer spills. Fixes: be23266b4a08 ("bpf: 4-byte precise clean_verifier_state") Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn> Link: https://lore.kernel.org/r/20260617-f01-06-half-slot-pointer-spill-v2-1-42b9cdc3cf64@mails.tsinghua.edu.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 3a354149bceacadbcf7d7b4766f5ef26a85892ab ]

__clean_func_state() cleans dead stack slots in 4-byte halves. When the
high half of a STACK_SPILL slot is dead and the low half remains live,
cleanup converts the live low half to STACK_MISC or STACK_ZERO and clears
the saved spilled_ptr metadata.

That conversion is safe only for scalar spills. For a pointer spill, this
metadata clear lets a later 32-bit fill from the still-live half avoid the
normal non-scalar register-fill check and be treated as an ordinary scalar
stack read.

Leave non-scalar spill slots intact in this half-live shape. This is
conservative for pruning and preserves the existing
check_stack_read_fixed_off() rejection path for partial fills from pointer
spills.

Fixes: be23266b4a08 ("bpf: 4-byte precise clean_verifier_state")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
Link: https://lore.kernel.org/r/20260617-f01-06-half-slot-pointer-spill-v2-1-42b9cdc3cf64@mails.tsinghua.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpf: Move state equivalence logic to states.c 2026-04-12T19:36:52+00:00 Alexei Starovoitov ast@kernel.org 2026-04-12T15:29:33+00:00 c82834a5a11f743f2926107d8f8150e80742b814 verifier.c is huge. Move is_state_visited() to states.c, so that all state equivalence logic is in one file. Mechanical move. No functional changes. Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260412152936.54262-5-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
verifier.c is huge. Move is_state_visited() to states.c,
so that all state equivalence logic is in one file.

Mechanical move. No functional changes.

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-5-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>