github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-21 12:20:02 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph
f29997a6d9
linux/kernel/bpf
History
Woojin Ji 69fdbe63e1 bpf: Preserve scalar zero spills for stack reads 
Stack reads can read back bytes that belong to a previously spilled scalar
constant zero. Today mark_reg_stack_read() only treats STACK_ZERO bytes as
known zero bytes, so the destination register can become unknown even
though every byte in the read range is known to be zero. This can lead to
rejecting otherwise valid programs once the loaded byte is used as a
pointer offset.

The original reproducer uses a variable-offset stack byte read emitted by
clang 22.1.6 at -O2/-O3 from a small helper-based BPF C program. Fixed
offset reads have a related mixed case as well: pure scalar-zero spill
reads are already handled, but a fixed read spanning both STACK_ZERO and
scalar const-zero STACK_SPILL bytes still falls back to unknown.

Teach mark_reg_stack_read() to also consider STACK_SPILL bytes backed by a
spilled scalar constant zero as zero bytes, and use that path for both
variable-offset stack reads and fixed-offset mixed reads. Keep the existing
pure register-fill behavior unchanged.

When a zero result depends on such a spill, mark the contributing stack
slots precise before accepting the const-zero result so pruning cannot
reuse a zero-spill state for a later non-zero spill state.

No deployed-program regression is currently known, so target bpf-next.

Assisted-by: opencode:gpt-5.5
Signed-off-by: Woojin Ji <random6.xyz@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260625-bpf-stack-var-off-zero-v1-v3-1-a068210a761b@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-06-25 17:55:25 -07:00
..
preload umd: Remove usermode driver framework 2025-07-26 21:03:04 +02:00
arena.c mm.git review status for mm-hotfixes-stable..mm-stable 2026-06-19 10:14:34 -07:00
arraymap.c bpf: Cancel special fields on map value recycle 2026-06-09 21:23:11 -07:00
backtrack.c bpf: Add precision marking and backtracking for stack argument slots 2026-05-13 09:27:30 -07:00
bloom_filter.c bpf: Lose const-ness of map in map_check_btf() 2026-02-27 15:39:00 -08:00
bpf_cgrp_storage.c bpf: Remove gfp_flags plumbing from bpf_local_storage_update() 2026-04-10 21:22:32 -07:00
bpf_inode_storage.c bpf: Remove gfp_flags plumbing from bpf_local_storage_update() 2026-04-10 21:22:32 -07:00
bpf_insn_array.c bpf: Lose const-ness of map in map_check_btf() 2026-02-27 15:39:00 -08:00
bpf_iter.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
bpf_local_storage.c bpf: Remove gfp_flags plumbing from bpf_local_storage_update() 2026-04-10 21:22:32 -07:00
bpf_lru_list.c bpf: Fix NMI/tracepoint re-entry deadlock on lru locks 2026-06-07 18:46:13 -07:00
bpf_lru_list.h bpf: Fix NMI/tracepoint re-entry deadlock on lru locks 2026-06-07 18:46:13 -07:00
bpf_lsm_proto.c bpf: annotate file argument as __nullable in bpf_lsm_mmap_file 2025-12-21 10:56:33 -08:00
bpf_lsm.c bpf: Disable xfrm_decode_session hook attachment 2026-06-22 20:08:37 -07:00
bpf_struct_ops.c bpf: Add struct bpf_tramp_node object 2026-06-07 10:03:01 -07:00
bpf_task_storage.c bpf: Remove gfp_flags plumbing from bpf_local_storage_update() 2026-04-10 21:22:32 -07:00
btf_iter.c bpf: Remove custom build rule 2024-08-30 08:55:26 -07:00
btf_relocate.c bpf: Remove custom build rule 2024-08-30 08:55:26 -07:00
btf.c bpf: Allow type tag BTF records to succeed other modifier records 2026-06-21 17:59:44 -07:00
cfg.c bpf: Check global subprog exception paths 2026-05-17 11:15:05 -07:00
cgroup_iter.c bpf: add new BPF_CGROUP_ITER_CHILDREN control option 2026-01-27 09:05:54 -08:00
cgroup.c bpf: Fix effective prog array index with BPF_F_PREORDER 2026-06-21 18:10:04 -07:00
check_btf.c bpf: Move BTF checking logic into check_btf.c 2026-04-12 12:37:04 -07:00
cnum_defs.h bpf: Export cnum_umin/umax() helpers for netronome driver 2026-04-27 10:09:48 -07:00
cnum.c bpf: representation and basic operations on circular numbers 2026-04-24 18:14:17 -07:00
const_fold.c bpf: Extend liveness analysis to track stack argument slots 2026-05-13 09:27:31 -07:00
core.c bpf: Tighten cgroup storage cookie checks for prog arrays 2026-06-10 16:16:46 -07:00
cpumap.c bpf: Add missing XDP_ABORTED handling in cpumap 2026-03-03 08:37:21 -08:00
cpumask.c bpf: Remove redundant KF_TRUSTED_ARGS flag from all kfuncs 2026-01-02 12:04:28 -08:00
crypto.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
devmap.c bpf: Run generic devmap egress prog on private skb 2026-06-12 18:21:01 -07:00
disasm.c bpf: disasm: add support for BPF_JMP|BPF_JA|BPF_X 2025-11-05 17:53:23 -08:00
disasm.h
dispatcher.c bpf: Add kernel symbol for struct_ops trampoline 2024-11-12 17:13:46 -08:00
dmabuf_iter.c bpf: Fix truncated dmabuf iterator reads 2025-12-09 23:48:34 -08:00
fixups.c bpf: Add support for tracing_multi link session 2026-06-07 10:03:01 -07:00
hashtab.c bpf: Cancel special fields on map value recycle 2026-06-09 21:23:11 -07:00
helpers.c mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
inode.c bpf-next-7.2 2026-06-17 09:18:14 +01:00
Kconfig bpf: Update the bpf_prog_calc_tag to use SHA256 2025-09-18 19:10:20 -07:00
kmem_cache_iter.c bpf: Add open coded version of kmem_cache iterator 2024-11-01 11:08:32 -07:00
link_iter.c bpf: Clean up individual BTF_ID code 2025-07-16 18:34:42 -07:00
liveness.c bpf: Fix arg_track_join log to use sa prefix for stack arg slots 2026-05-16 17:46:16 -07:00
local_storage.c bpf: fix end-of-list detection in cgroup_storage_get_next_key() 2026-04-05 18:45:05 -07:00
log.c bpf: Refactor object relationship tracking and fix dynptr UAF bug 2026-06-01 18:31:41 -07:00
lpm_trie.c bpf: Allow LPM map access from sleepable BPF programs 2026-06-09 12:42:22 -07:00
Makefile bpf: representation and basic operations on circular numbers 2026-04-24 18:14:17 -07:00
map_in_map.c bpf: Reject exclusive maps as inner maps in map-in-map 2026-06-01 18:36:40 -07:00
map_in_map.h bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2023-12-04 17:50:26 -08:00
map_iter.c bpf: Implement iteration ops for resizable hashtab 2026-06-05 08:00:08 -07:00
memalloc.c bpf: Retire rcu_trace_implies_rcu_gp() 2026-04-07 12:24:49 -07:00
mmap_unlock_work.h
mprog.c bpf: Handle bpf_mprog_query with NULL entry 2023-10-06 17:11:20 -07:00
net_namespace.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
offload.c bpf: Fix use-after-free in offloaded map/prog info fill 2026-04-09 13:24:32 -07:00
percpu_freelist.c bpf: Convert percpu_freelist.c to rqspinlock 2025-03-19 08:03:05 -07:00
percpu_freelist.h bpf: Convert percpu_freelist.c to rqspinlock 2025-03-19 08:03:05 -07:00
prog_iter.c bpf: Clean up individual BTF_ID code 2025-07-16 18:34:42 -07:00
queue_stack_maps.c bpf: Convert queue_stack map to rqspinlock 2025-04-10 12:51:10 -07:00
range_tree.c bpf: arena: Reintroduce memcg accounting 2026-01-02 14:31:59 -08:00
range_tree.h bpf: Introduce range_tree data structure and use it in bpf arena 2024-11-13 13:52:45 -08:00
relo_core.c bpf: Remove custom build rule 2024-08-30 08:55:26 -07:00
reuseport_array.c bpf: Use sockfd_put() helper 2024-08-30 08:57:47 -07:00
ringbuf.c bpf: Add SPDX license identifiers to a few files 2026-01-16 14:50:00 -08:00
rqspinlock.c mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
rqspinlock.h rqspinlock: Protect waiters in queue from stalls 2025-03-19 08:03:05 -07:00
stackmap.c bpf: Fix build_id caching in stack_map_get_build_id_offset() 2026-06-21 17:58:14 -07:00
states.c bpf: Preserve pointer spill metadata during half-slot cleanup 2026-06-22 13:39:34 -07:00
stream.c bpf: Add bpf_stream_print_stack stack dumping kfunc 2026-02-03 10:41:16 -08:00
syscall.c bpf: Fix BPF_PROG_ASSOC_STRUCT_OPS last field check 2026-06-21 18:09:07 -07:00
sysfs_btf.c Driver core changes for 6.17-rc1 2025-07-29 12:15:39 -07:00
task_iter.c bpf: return VMA snapshot from task_vma iterator 2026-04-10 12:05:16 -07:00
tcx.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
tnum.c bpf: Simplify tnum_step() 2026-03-24 08:45:29 -07:00
token.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
trampoline.c bpf: Add support for tracing_multi link session 2026-06-07 10:03:01 -07:00
verifier.c bpf: Preserve scalar zero spills for stack reads 2026-06-25 17:55:25 -07:00