From: Stanislav Fomichev <sdf@google.com>
Date: Fri, 14 Oct 2022 17:24:44 -0700
Subject: bpf: prevent decl_tag from being referenced in func_proto
Patch-mainline: v6.1-rc3
Git-commit: ea68376c8bed5cd156900852aada20c3a0874d17
References: git-fixes
Syzkaller was able to hit the following issue:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3609 at kernel/bpf/btf.c:1946
btf_type_id_size+0x2d5/0x9d0 kernel/bpf/btf.c:1946
Modules linked in:
CPU: 0 PID: 3609 Comm: syz-executor361 Not tainted
6.0.0-syzkaller-02734-g0326074ff465 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 09/22/2022
RIP: 0010:btf_type_id_size+0x2d5/0x9d0 kernel/bpf/btf.c:1946
Code: ef e8 7f 8e e4 ff 41 83 ff 0b 77 28 f6 44 24 10 18 75 3f e8 6d 91
e4 ff 44 89 fe bf 0e 00 00 00 e8 20 8e e4 ff e8 5b 91 e4 ff <0f> 0b 45
31 f6 e9 98 02 00 00 41 83 ff 12 74 18 e8 46 91 e4 ff 44
RSP: 0018:ffffc90003cefb40 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: ffff8880259c0000 RSI: ffffffff81968415 RDI: 0000000000000005
RBP: ffff88801270ca00 R08: 0000000000000005 R09: 000000000000000e
R10: 0000000000000011 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000011 R14: ffff888026ee6424 R15: 0000000000000011
FS: 000055555641b300(0000) GS:ffff8880b9a00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000f2e258 CR3: 000000007110e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
btf_func_proto_check kernel/bpf/btf.c:4447 [inline]
btf_check_all_types kernel/bpf/btf.c:4723 [inline]
btf_parse_type_sec kernel/bpf/btf.c:4752 [inline]
btf_parse kernel/bpf/btf.c:5026 [inline]
btf_new_fd+0x1926/0x1e70 kernel/bpf/btf.c:6892
bpf_btf_load kernel/bpf/syscall.c:4324 [inline]
__sys_bpf+0xb7d/0x4cf0 kernel/bpf/syscall.c:5010
__do_sys_bpf kernel/bpf/syscall.c:5069 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5067 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:5067
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0fbae41c69
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc8aeb6228 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0fbae41c69
RDX: 0000000000000020 RSI: 0000000020000140 RDI: 0000000000000012
RBP: 00007f0fbae05e10 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007f0fbae05ea0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Looks like it tries to create a func_proto which return type is
decl_tag. For the details, see Martin's spot on analysis in [0].
0: https://lore.kernel.org/bpf/CAKH8qBuQDLva_hHxxBuZzyAcYNO4ejhovz6TQeVSk8HY-2SO6g@mail.gmail.com/T/#mea6524b3fcd6298347432226e81b1e6155efc62c
Cc: Yonghong Song <yhs@fb.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Fixes: bd16dee66ae4 ("bpf: Add BTF_KIND_DECL_TAG typedef support")
Reported-by: syzbot+d8bd751aef7c6b39a344@syzkaller.appspotmail.com
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221015002444.2680969-2-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
kernel/bpf/btf.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4325,6 +4325,11 @@ static int btf_func_proto_check(struct b
return -EINVAL;
}
+ if (btf_type_is_resolve_source_only(ret_type)) {
+ btf_verifier_log_type(env, t, "Invalid return type");
+ return -EINVAL;
+ }
+
if (btf_type_needs_resolve(ret_type) &&
!env_type_is_resolved(env, ret_type_id)) {
err = btf_resolve(env, ret_type, ret_type_id);