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9adec73349
kernel_optimize_test/kernel/bpf
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Daniel Borkmann 9adec73349 bpf: Fix incorrect verifier simulation around jmp32's jeq/jne 
commit a12ca6277eca6aeeccf66e840c23a2b520e24c8f upstream.

Kuee reported a quirk in the jmp32's jeq/jne simulation, namely that the
register value does not match expectations for the fall-through path. For
example:

Before fix:

  0: R1=ctx(off=0,imm=0) R10=fp0
  0: (b7) r2 = 0                        ; R2_w=P0
  1: (b7) r6 = 563                      ; R6_w=P563
  2: (87) r2 = -r2                      ; R2_w=Pscalar()
  3: (87) r2 = -r2                      ; R2_w=Pscalar()
  4: (4c) w2 |= w6                      ; R2_w=Pscalar(umin=563,umax=4294967295,var_off=(0x233; 0xfffffdcc),s32_min=-2147483085) R6_w=P563
  5: (56) if w2 != 0x8 goto pc+1        ; R2_w=P571  <--- [*]
  6: (95) exit
  R0 !read_ok

After fix:

  0: R1=ctx(off=0,imm=0) R10=fp0
  0: (b7) r2 = 0                        ; R2_w=P0
  1: (b7) r6 = 563                      ; R6_w=P563
  2: (87) r2 = -r2                      ; R2_w=Pscalar()
  3: (87) r2 = -r2                      ; R2_w=Pscalar()
  4: (4c) w2 |= w6                      ; R2_w=Pscalar(umin=563,umax=4294967295,var_off=(0x233; 0xfffffdcc),s32_min=-2147483085) R6_w=P563
  5: (56) if w2 != 0x8 goto pc+1        ; R2_w=P8  <--- [*]
  6: (95) exit
  R0 !read_ok

As can be seen on line 5 for the branch fall-through path in R2 [*] is that
given condition w2 != 0x8 is false, verifier should conclude that r2 = 8 as
upper 32 bit are known to be zero. However, verifier incorrectly concludes
that r2 = 571 which is far off.

The problem is it only marks false{true}_reg as known in the switch for JE/NE
case, but at the end of the function, it uses {false,true}_{64,32}off to
update {false,true}_reg->var_off and they still hold the prior value of
{false,true}_reg->var_off before it got marked as known. The subsequent
__reg_combine_32_into_64() then propagates this old var_off and derives new
bounds. The information between min/max bounds on {false,true}_reg from
setting the register to known const combined with the {false,true}_reg->var_off
based on the old information then derives wrong register data.

Fix it by detangling the BPF_JEQ/BPF_JNE cases and updating relevant
{false,true}_{64,32}off tnums along with the register marking to known
constant.

Fixes: 3f50f132d8 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Kuee K1r0a <liulin063@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220701124727.11153-1-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-12 16:32:17 +02:00
..
preload bpf: Fix umd memory leak in copy_process() 2021-03-30 14:32:03 +02:00
arraymap.c bpf: Fix potential race in tail call compatibility check 2021-11-02 19:48:21 +01:00
bpf_inode_storage.c bpf: Change inode_storage's lookup_elem return value from NULL to -EBADF 2021-03-30 14:31:56 +02:00
bpf_iter.c bpf: Fix an unitialized value in bpf_iter 2021-03-04 11:37:33 +01:00
bpf_local_storage.c bpf: Use hlist_add_head_rcu when linking to local_storage 2020-09-19 01:12:35 +02:00
bpf_lru_list.c bpf_lru_list: Read double-checked variable once without lock 2021-03-04 11:37:29 +01:00
bpf_lru_list.h bpf: Fix a typo "inacitve" -> "inactive" 2020-04-06 21:54:10 +02:00
bpf_lsm.c bpf: Update verification logic for LSM programs 2020-11-06 13:15:21 -08:00
bpf_struct_ops_types.h bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
bpf_struct_ops.c bpf: Handle return value of BPF_PROG_TYPE_STRUCT_OPS prog 2021-10-06 15:55:50 +02:00
btf.c bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD) 2022-01-27 10:53:54 +01:00
cgroup.c bpf, cgroup: Fix problematic bounds check 2021-02-10 09:29:12 +01:00
core.c bpf: Fix probe read error in ___bpf_prog_run() 2022-06-14 18:32:35 +02:00
cpumap.c bpf, cpumap: Remove rcpu pointer from cpu_map_build_skb signature 2020-09-28 23:30:42 +02:00
devmap.c bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc 2021-12-17 10:14:41 +01:00
disasm.c bpf: Introduce BPF nospec instruction for mitigating Spectre v4 2021-08-04 12:46:44 +02:00
disasm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295 2019-06-05 17:36:38 +02:00
dispatcher.c bpf: Remove bpf_image tree 2020-03-13 12:49:52 -07:00
hashtab.c bpf: Fix integer overflow involving bucket_size 2021-08-18 08:59:10 +02:00
helpers.c bpf: Fix potentially incorrect results with bpf_get_local_storage() 2021-09-03 10:09:31 +02:00
inode.c bpf: link: Refuse non-O_RDWR flags in BPF_OBJ_GET 2021-04-14 08:42:00 +02:00
local_storage.c bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper 2021-09-03 10:09:21 +02:00
lpm_trie.c bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
Makefile bpf: Don't rely on GCC __attribute__((optimize)) to disable GCSE 2020-10-29 20:01:46 -07:00
map_in_map.c bpf: Relax max_entries check for most of the inner map types 2020-08-28 15:41:30 +02:00
map_in_map.h bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
map_iter.c bpf: Implement link_query callbacks in map element iterators 2020-08-21 14:01:39 -07:00
net_namespace.c bpf: Add support for forced LINK_DETACH command 2020-08-01 20:38:28 -07:00
offload.c bpf, offload: Replace bitwise AND by logical AND in bpf_prog_offload_info_fill 2020-02-17 16:53:49 +01:00
percpu_freelist.c bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
percpu_freelist.h bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
prog_iter.c bpf: Refactor bpf_iter_reg to have separate seq_info member 2020-07-25 20:16:32 -07:00
queue_stack_maps.c bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
reuseport_array.c bpf, net: Rework cookie generator as per-cpu one 2020-09-30 11:50:35 -07:00
ringbuf.c bpf: Use VM_MAP instead of VM_ALLOC for ringbuf 2022-02-08 18:30:39 +01:00
stackmap.c bpf: Fix incorrect memory charge cost calculation in stack_map_alloc() 2022-06-22 14:13:12 +02:00
syscall.c bpf: Add schedule points in batch ops 2022-03-02 11:42:49 +01:00
sysfs_btf.c bpf: Fix sysfs export of empty BTF section 2020-09-21 21:50:24 +02:00
task_iter.c bpf: Save correct stopping point in file seq iteration 2021-01-19 18:27:28 +01:00
tnum.c bpf: Verifier, do explicit ALU32 bounds tracking 2020-03-30 14:59:53 -07:00
trampoline.c bpf: Fix potential array overflow in bpf_trampoline_get_progs() 2022-06-06 08:42:45 +02:00
verifier.c bpf: Fix incorrect verifier simulation around jmp32's jeq/jne 2022-07-12 16:32:17 +02:00