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bpf: Introduce bpf_arch_text_invalidate for bpf_prog_pack

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Introduce bpf_arch_text_invalidate and use it to fill unused part of the
bpf_prog_pack with illegal instructions when a BPF program is freed.

Fixes: 57631054fa ("bpf: Introduce bpf_prog_pack allocator")
Fixes: 33c9805860 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220520235758.1858153-4-song@kernel.org
This commit is contained in:
Song Liu 2022-05-20 16:57:53 -07:00 committed by Daniel Borkmann
parent aadd1b678e
commit fe736565ef
3 changed files with 14 additions and 0 deletions
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5
arch/x86/net/bpf_jit_comp.c
View File

@ -228,6 +228,11 @@ static void jit_fill_hole(void *area, unsigned int size)
memset(area, 0xcc, size);
}
int bpf_arch_text_invalidate(void *dst, size_t len)
{
return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len));
}
struct jit_context {
int cleanup_addr; /* Epilogue code offset */

1
include/linux/bpf.h
View File

@ -2365,6 +2365,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
void *addr1, void *addr2);
void *bpf_arch_text_copy(void *dst, void *src, size_t len);
int bpf_arch_text_invalidate(void *dst, size_t len);
struct btf_id_set;
bool btf_id_set_contains(const struct btf_id_set *set, u32 id);

8
kernel/bpf/core.c
View File

@ -968,6 +968,9 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr)
nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size);
pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT;
WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size),
"bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n");
bitmap_clear(pack->bitmap, pos, nbits);
if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0,
bpf_prog_chunk_count(), 0) == 0) {
@ -2740,6 +2743,11 @@ void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len)
return ERR_PTR(-ENOTSUPP);
}
int __weak bpf_arch_text_invalidate(void *dst, size_t len)
{
return -ENOTSUPP;
}
DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
EXPORT_SYMBOL(bpf_stats_enabled_key);