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Revert "bpf: track changes_pkt_data property for global functions"

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This reverts commit 1d572c6048 which is
commit 51081a3f25c742da5a659d7fc6fd77ebfdd555be upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I3c570f3e9aa480007914e6ad7a166afe1dbfba55
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Greg Kroah-Hartman
2025-05-20 09:52:21 +00:00
parent d9ca1c7ed5
commit a4f1e3a7a1
2 changed files with 1 additions and 32 deletions
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1
include/linux/bpf_verifier.h
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@@ -669,7 +669,6 @@ struct bpf_subprog_info {
bool args_cached: 1;
/* true if bpf_fastcall stack region is used by functions that can't be inlined */
bool keep_fastcall_stack: 1;
bool changes_pkt_data: 1;
u8 arg_cnt;
struct bpf_subprog_arg_info args[MAX_BPF_FUNC_REG_ARGS];

32
kernel/bpf/verifier.c
View File

@@ -9831,8 +9831,6 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
subprog, sub_name);
if (env->subprog_info[subprog].changes_pkt_data)
clear_all_pkt_pointers(env);
/* mark global subprog for verifying after main prog */
subprog_aux(env, subprog)->called = true;
clear_caller_saved_regs(env, caller->regs);
@@ -16023,29 +16021,6 @@ enforce_retval:
return 0;
}
static void mark_subprog_changes_pkt_data(struct bpf_verifier_env *env, int off)
{
struct bpf_subprog_info *subprog;
subprog = find_containing_subprog(env, off);
subprog->changes_pkt_data = true;
}
/* 't' is an index of a call-site.
* 'w' is a callee entry point.
* Eventually this function would be called when env->cfg.insn_state[w] == EXPLORED.
* Rely on DFS traversal order and absence of recursive calls to guarantee that
* callee's change_pkt_data marks would be correct at that moment.
*/
static void merge_callee_effects(struct bpf_verifier_env *env, int t, int w)
{
struct bpf_subprog_info *caller, *callee;
caller = find_containing_subprog(env, t);
callee = find_containing_subprog(env, w);
caller->changes_pkt_data |= callee->changes_pkt_data;
}
/* non-recursive DFS pseudo code
* 1 procedure DFS-iterative(G,v):
* 2 label v as discovered
@@ -16179,7 +16154,6 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns,
bool visit_callee)
{
int ret, insn_sz;
int w;
insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1;
ret = push_insn(t, t + insn_sz, FALLTHROUGH, env);
@@ -16191,10 +16165,8 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns,
mark_jmp_point(env, t + insn_sz);
if (visit_callee) {
w = t + insns[t].imm + 1;
mark_prune_point(env, t);
merge_callee_effects(env, t, w);
ret = push_insn(t, w, BRANCH, env);
ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env);
}
return ret;
}
@@ -16514,8 +16486,6 @@ static int visit_insn(int t, struct bpf_verifier_env *env)
mark_prune_point(env, t);
mark_jmp_point(env, t);
}
if (bpf_helper_call(insn) && bpf_helper_changes_pkt_data(insn->imm))
mark_subprog_changes_pkt_data(env, t);
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
struct bpf_kfunc_call_arg_meta meta;