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bpf: Prevent increasing bpf_jit_limit above max

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[ Upstream commit fadb7ff1a6 ]

Restrict bpf_jit_limit to the maximum supported by the arch's JIT.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211014142554.53120-4-lmb@cloudflare.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Lorenz Bauer
2021-10-14 15:25:53 +01:00
committed by Greg Kroah-Hartman
parent df8665c398
commit de649ec7ad
3 changed files with 5 additions and 2 deletions
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4
kernel/bpf/core.c
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@@ -523,6 +523,7 @@ int bpf_jit_enable __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);
int bpf_jit_harden __read_mostly;
int bpf_jit_kallsyms __read_mostly;
long bpf_jit_limit __read_mostly;
long bpf_jit_limit_max __read_mostly;
static __always_inline void
bpf_get_prog_addr_region(const struct bpf_prog *prog,
@@ -759,7 +760,8 @@ u64 __weak bpf_jit_alloc_exec_limit(void)
static int __init bpf_jit_charge_init(void)
{
/* Only used as heuristic here to derive limit. */
bpf_jit_limit = min_t(u64, round_up(bpf_jit_alloc_exec_limit() >> 2,
bpf_jit_limit_max = bpf_jit_alloc_exec_limit();
bpf_jit_limit = min_t(u64, round_up(bpf_jit_limit_max >> 2,
PAGE_SIZE), LONG_MAX);
return 0;
}