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5415ccd50a
linux/kernel/bpf
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Kumar Kartikeya Dwivedi 5415ccd50a bpf: Fix max stack depth check for async callbacks 
The check_max_stack_depth pass happens after the verifier's symbolic
execution, and attempts to walk the call graph of the BPF program,
ensuring that the stack usage stays within bounds for all possible call
chains. There are two cases to consider: bpf_pseudo_func and
bpf_pseudo_call. In the former case, the callback pointer is loaded into
a register, and is assumed that it is passed to some helper later which
calls it (however there is no way to be sure), but the check remains
conservative and accounts the stack usage anyway. For this particular
case, asynchronous callbacks are skipped as they execute asynchronously
when their corresponding event fires.

The case of bpf_pseudo_call is simpler and we know that the call is
definitely made, hence the stack depth of the subprog is accounted for.

However, the current check still skips an asynchronous callback even if
a bpf_pseudo_call was made for it. This is erroneous, as it will miss
accounting for the stack usage of the asynchronous callback, which can
be used to breach the maximum stack depth limit.

Fix this by only skipping asynchronous callbacks when the instruction is
not a pseudo call to the subprog.

Fixes: 7ddc80a476 ("bpf: Teach stack depth check about async callbacks.")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230705144730.235802-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-07-05 19:14:54 -07:00
..
preload bpf: Replace all non-returning strlcpy with strscpy 2023-05-31 13:04:20 +02:00
arraymap.c bpf: return long from bpf_map_ops funcs 2023-03-22 15:11:30 -07:00
bloom_filter.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
bpf_cgrp_storage.c bpf: Teach verifier that certain helpers accept NULL pointer. 2023-04-04 16:57:16 -07:00
bpf_inode_storage.c Networking changes for 6.4. 2023-04-26 16:07:23 -07:00
bpf_iter.c bpf: implement numbers iterator 2023-03-08 16:19:51 -08:00
bpf_local_storage.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
bpf_lru_list.c bpf: Address KCSAN report on bpf_lru_list 2023-05-12 12:01:03 -07:00
bpf_lru_list.h bpf: Address KCSAN report on bpf_lru_list 2023-05-12 12:01:03 -07:00
bpf_lsm.c bpf: Fix the kernel crash caused by bpf_setsockopt(). 2023-01-26 23:26:40 -08:00
bpf_struct_ops_types.h bpf: Add dummy BPF STRUCT_OPS for test purpose 2021-11-01 14:10:00 -07:00
bpf_struct_ops.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
bpf_task_storage.c bpf: Teach verifier that certain helpers accept NULL pointer. 2023-04-04 16:57:16 -07:00
btf.c bpf, btf: Warn but return no error for NULL btf from __register_btf_kfunc_id_set() 2023-07-03 18:48:09 +02:00
cgroup_iter.c cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers 2023-03-17 12:07:13 -10:00
cgroup.c bpf-next-for-netdev 2023-05-16 19:50:05 -07:00
core.c bpf: Hide unused bpf_patch_call_args 2023-06-12 19:00:08 +02:00
cpumap.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
cpumask.c bpf: Replace bpf_cpumask_any* with bpf_cpumask_any_distribute* 2023-06-12 15:09:11 -07:00
devmap.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
disasm.c
disasm.h
dispatcher.c bpf: Synchronize dispatcher update with bpf_dispatcher_xdp_func 2022-12-14 12:02:14 -08:00
hashtab.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
helpers.c bpf: Make bpf_refcount_acquire fallible for non-owning refs 2023-06-05 13:17:20 -07:00
inode.c bpf: Support O_PATH FDs in BPF_OBJ_PIN and BPF_OBJ_GET commands 2023-05-23 23:31:42 +02:00
Kconfig rcu: Make the TASKS_RCU Kconfig option be selected 2022-04-20 16:52:58 -07:00
link_iter.c bpf: Add bpf_link iterator 2022-05-10 11:20:45 -07:00
local_storage.c cgroup changes for v6.4-rc1 2023-04-29 10:05:22 -07:00
log.c bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log 2023-05-16 22:34:50 -07:00
lpm_trie.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
Makefile bpf: Split off basic BPF verifier log into separate file 2023-04-11 18:05:42 +02:00
map_in_map.c bpf: Fix elem_size not being set for inner maps 2023-06-02 16:22:12 -07:00
map_in_map.h
map_iter.c bpf: Introduce MEM_RDONLY flag 2021-12-18 13:27:41 -08:00
memalloc.c bpf: Factor out a common helper free_all() 2023-06-06 13:40:07 -07:00
mmap_unlock_work.h bpf: Introduce helper bpf_find_vma 2021-11-07 11:54:51 -08:00
net_namespace.c net: Add includes masked by netdevice.h including uapi/bpf.h 2021-12-29 20:03:05 -08:00
offload.c bpf: netdev: init the offload table earlier 2023-05-15 07:07:41 -07:00
percpu_freelist.c bpf: Initialize same number of free nodes for each pcpu_freelist 2022-11-11 12:05:14 -08:00
percpu_freelist.h
prog_iter.c
queue_stack_maps.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
reuseport_array.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
ringbuf.c bpf: return long from bpf_map_ops funcs 2023-03-22 15:11:30 -07:00
stackmap.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
syscall.c bpf-next-for-netdev 2023-06-24 14:52:28 -07:00
sysfs_btf.c
task_iter.c bpf: keep a reference to the mm, in case the task is dead. 2022-12-28 14:11:48 -08:00
tnum.c
trampoline.c bpf: Fix memleak due to fentry attach failure 2023-05-15 23:41:59 +02:00
verifier.c bpf: Fix max stack depth check for async callbacks 2023-07-05 19:14:54 -07:00