sk_protocol lives in struct sock, not in struct sock_common. A timewait
or request sock handed to bpf_sock_destroy() by the tcp iterator is
neither, so reading sk->sk_protocol runs past the object:
==================================================================
BUG: KASAN: slab-out-of-bounds in bpf_sock_destroy+0xc7/0xe0
Read of size 2 at addr ffff8881047d11b4 by task test_progs/428
Tainted: [W]=WARN
Call Trace:
<TASK>
dump_stack_lvl+0x91/0xf0
print_report+0xd1/0x630
kasan_report+0xf3/0x130
__asan_report_load2_noabort+0x14/0x30
bpf_sock_destroy+0xc7/0xe0
bpf_prog_c3dd61f9d9cd9f37_iter_tcp6_timewait+0x9f/0xb7
bpf_iter_run_prog+0x538/0xde0
bpf_iter_tcp_seq_show+0x26b/0x4b0
bpf_seq_read+0x424/0x1210
vfs_read+0x197/0xe40
ksys_read+0x119/0x240
__x64_sys_read+0x72/0xc0
x64_sys_call+0x647/0x27e0
do_syscall_64+0xe5/0x610
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Only check sk_protocol on full socks. tcp_abort() already knows how to
deal with TIME_WAIT and NEW_SYN_RECV socks. Also fix the comment, it
never matched the code.
Fixes: 4ddbcb886268 ("bpf: Add bpf_sock_destroy kfunc")
Reported-by: Xiang Mei (Microsoft) <[email protected]>
Closes: https://lore.kernel.org/bpf/[email protected]/
Signed-off-by: Jiayuan Chen <[email protected]>
---
net/core/filter.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 61940e753552..1bbb72138ac6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -12912,8 +12912,8 @@ __bpf_kfunc_start_defs();
* @sock: Pointer to socket to be destroyed
*
* Return:
- * On error, may return EPROTONOSUPPORT, EINVAL.
- * EPROTONOSUPPORT if protocol specific destroy handler is not supported.
+ * On error, may return EOPNOTSUPP, EINVAL.
+ * EOPNOTSUPP if protocol specific destroy handler is not supported.
* 0 otherwise
*/
__bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
@@ -12925,8 +12925,12 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common
*sock)
* Supporting protocols will need to acquire sock lock in the BPF
context
* prior to invoking this kfunc.
*/
- if (!sk->sk_prot->diag_destroy || (sk->sk_protocol != IPPROTO_TCP &&
- sk->sk_protocol != IPPROTO_UDP))
+ if (!sk->sk_prot->diag_destroy)
+ return -EOPNOTSUPP;
+
+ if (sk_fullsock(sk) &&
+ sk->sk_protocol != IPPROTO_TCP &&
+ sk->sk_protocol != IPPROTO_UDP)
return -EOPNOTSUPP;
return sk->sk_prot->diag_destroy(sk, ECONNABORTED);
--
2.43.0
