From: Song Liu song@kernel.org
[ Upstream commit 1d5f82d9dd477d5c66e0214a68c3e4f308eadd6d ]
syzbot reported a few issues with bpf_prog_pack [1], [2]. This only happens with multiple subprogs. In jit_subprogs(), we first call bpf_int_jit_compile() on each sub program. And then, we call it on each sub program again. jit_data is not freed in the first call of bpf_int_jit_compile(). Similarly we don't call bpf_jit_binary_pack_finalize() in the first call of bpf_int_jit_compile().
If bpf_int_jit_compile() failed for one sub program, we will call bpf_jit_binary_pack_finalize() for this sub program. However, we don't have a chance to call it for other sub programs. Then we will hit "goto out_free" in jit_subprogs(), and call bpf_jit_free on some subprograms that haven't got bpf_jit_binary_pack_finalize() yet.
At this point, bpf_jit_binary_pack_free() is called and the whole 2MB page is freed erroneously.
Fix this with a custom bpf_jit_free() for x86_64, which calls bpf_jit_binary_pack_finalize() if necessary. Also, with custom bpf_jit_free(), bpf_prog_aux->use_bpf_prog_pack is not needed any more, remove it.
Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc") [1] https://syzkaller.appspot.com/bug?extid=2f649ec6d2eea1495a8f [2] https://syzkaller.appspot.com/bug?extid=87f65c75f4a72db05445 Reported-by: syzbot+2f649ec6d2eea1495a8f@syzkaller.appspotmail.com Reported-by: syzbot+87f65c75f4a72db05445@syzkaller.appspotmail.com Signed-off-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20220706002612.4013790-1-song@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/net/bpf_jit_comp.c | 25 +++++++++++++++++++++++++ include/linux/bpf.h | 1 - include/linux/filter.h | 8 ++++++++ kernel/bpf/core.c | 29 ++++++++++++----------------- 4 files changed, 45 insertions(+), 18 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 124456bb23b9..400117f630b8 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2483,3 +2483,28 @@ bool bpf_jit_supports_subprog_tailcalls(void) { return true; } + +void bpf_jit_free(struct bpf_prog *prog) +{ + if (prog->jited) { + struct x64_jit_data *jit_data = prog->aux->jit_data; + struct bpf_binary_header *hdr; + + /* + * If we fail the final pass of JIT (from jit_subprogs), + * the program may not be finalized yet. Call finalize here + * before freeing it. + */ + if (jit_data) { + bpf_jit_binary_pack_finalize(prog, jit_data->header, + jit_data->rw_header); + kvfree(jit_data->addrs); + kfree(jit_data); + } + hdr = bpf_jit_binary_pack_hdr(prog); + bpf_jit_binary_pack_free(hdr, NULL); + WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog)); + } + + bpf_prog_unlock_free(prog); +} diff --git a/include/linux/bpf.h b/include/linux/bpf.h index b5d19a6f7d24..492e114b4e32 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -960,7 +960,6 @@ struct bpf_prog_aux { bool sleepable; bool tail_call_reachable; bool xdp_has_frags; - bool use_bpf_prog_pack; /* BTF_KIND_FUNC_PROTO for valid attach_btf_id */ const struct btf_type *attach_func_proto; /* function name for valid attach_btf_id */ diff --git a/include/linux/filter.h b/include/linux/filter.h index d9a0db845b50..8fd2e2f58eeb 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1061,6 +1061,14 @@ u64 bpf_jit_alloc_exec_limit(void); void *bpf_jit_alloc_exec(unsigned long size); void bpf_jit_free_exec(void *addr); void bpf_jit_free(struct bpf_prog *fp); +struct bpf_binary_header * +bpf_jit_binary_pack_hdr(const struct bpf_prog *fp); + +static inline bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) +{ + return list_empty(&fp->aux->ksym.lnode) || + fp->aux->ksym.lnode.prev == LIST_POISON2; +}
struct bpf_binary_header * bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **ro_image, diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 7a1ce697689b..483bee45ead5 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -649,12 +649,6 @@ static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp) return fp->jited && !bpf_prog_was_classic(fp); }
-static bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) -{ - return list_empty(&fp->aux->ksym.lnode) || - fp->aux->ksym.lnode.prev == LIST_POISON2; -} - void bpf_prog_kallsyms_add(struct bpf_prog *fp) { if (!bpf_prog_kallsyms_candidate(fp) || @@ -1149,7 +1143,6 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog, bpf_prog_pack_free(ro_header); return PTR_ERR(ptr); } - prog->aux->use_bpf_prog_pack = true; return 0; }
@@ -1173,17 +1166,23 @@ void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header, bpf_jit_uncharge_modmem(size); }
+struct bpf_binary_header * +bpf_jit_binary_pack_hdr(const struct bpf_prog *fp) +{ + unsigned long real_start = (unsigned long)fp->bpf_func; + unsigned long addr; + + addr = real_start & BPF_PROG_CHUNK_MASK; + return (void *)addr; +} + static inline struct bpf_binary_header * bpf_jit_binary_hdr(const struct bpf_prog *fp) { unsigned long real_start = (unsigned long)fp->bpf_func; unsigned long addr;
- if (fp->aux->use_bpf_prog_pack) - addr = real_start & BPF_PROG_CHUNK_MASK; - else - addr = real_start & PAGE_MASK; - + addr = real_start & PAGE_MASK; return (void *)addr; }
@@ -1196,11 +1195,7 @@ void __weak bpf_jit_free(struct bpf_prog *fp) if (fp->jited) { struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp);
- if (fp->aux->use_bpf_prog_pack) - bpf_jit_binary_pack_free(hdr, NULL /* rw_buffer */); - else - bpf_jit_binary_free(hdr); - + bpf_jit_binary_free(hdr); WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); }