Re: [PATCH bpf v2 1/3] bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destroy()
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-09-07 23:23:20
Also in:
bpf, linux-kselftest, lkml
On Sun, Sep 6, 2026 at 12:42 AM Jiayuan Chen [off-list ref] wrote:
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) <redacted>
Closes: https://lore.kernel.org/bpf/20260702224519.800135-1-xmei5@asu.edu/ (local)
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>