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bpf: Fix invalid mem access when update_effective_progs fails in __cgroup_bpf_detach #6294

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bpf: Fix invalid mem access when update_effective_progs fails in __cgroup_bpf_detach #6294

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6 changes: 6 additions & 0 deletions include/linux/bpf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2212,6 +2212,12 @@ struct bpf_prog_array {
struct bpf_prog_array_item items[];
};

struct bpf_prog_dummy {
struct bpf_prog prog;
};

extern struct bpf_prog_dummy dummy_bpf_prog;

struct bpf_empty_prog_array {
struct bpf_prog_array hdr;
struct bpf_prog *null_prog;
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5 changes: 3 additions & 2 deletions kernel/bpf/cgroup.c
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Expand Up @@ -77,15 +77,16 @@ bpf_prog_run_array_cg(const struct cgroup_bpf *cgrp,
item = &array->items[0];
old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
while ((prog = READ_ONCE(item->prog))) {
run_ctx.prog_item = item;
run_ctx.prog_item = item++;
if (prog == &dummy_bpf_prog.prog)
continue;
func_ret = run_prog(prog, ctx);
if (ret_flags) {
*(ret_flags) |= (func_ret >> 1);
func_ret &= 1;
}
if (!func_ret && !IS_ERR_VALUE((long)run_ctx.retval))
run_ctx.retval = -EPERM;
item++;
}
bpf_reset_run_ctx(old_run_ctx);
rcu_read_unlock_migrate();
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5 changes: 2 additions & 3 deletions kernel/bpf/core.c
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Expand Up @@ -2536,13 +2536,12 @@ static unsigned int __bpf_prog_ret1(const void *ctx,
return 1;
}

static struct bpf_prog_dummy {
struct bpf_prog prog;
} dummy_bpf_prog = {
struct bpf_prog_dummy dummy_bpf_prog = {
.prog = {
.bpf_func = __bpf_prog_ret1,
},
};
EXPORT_SYMBOL(dummy_bpf_prog);

struct bpf_empty_prog_array bpf_empty_prog_array = {
.null_prog = NULL,
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