diff options
| author | Levi Zim <rsworktech@outlook.com> | 2024-11-30 14:38:23 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2024-12-20 22:53:36 +0100 |
| commit | 5153a75ef34b3f7478ca918044d0f05eed8fb3f9 (patch) | |
| tree | b6ae00964375d12887d987d35b42b61f24039f16 /net | |
| parent | skmsg: Return copied bytes in sk_msg_memcopy_from_iter (diff) | |
| download | linux-5153a75ef34b3f7478ca918044d0f05eed8fb3f9.tar.xz linux-5153a75ef34b3f7478ca918044d0f05eed8fb3f9.zip | |
tcp_bpf: Fix copied value in tcp_bpf_sendmsg
bpf kselftest sockhash::test_txmsg_cork_hangs in test_sockmap.c triggers a
kernel NULL pointer dereference:
BUG: kernel NULL pointer dereference, address: 0000000000000008
? __die_body+0x6e/0xb0
? __die+0x8b/0xa0
? page_fault_oops+0x358/0x3c0
? local_clock+0x19/0x30
? lock_release+0x11b/0x440
? kernelmode_fixup_or_oops+0x54/0x60
? __bad_area_nosemaphore+0x4f/0x210
? mmap_read_unlock+0x13/0x30
? bad_area_nosemaphore+0x16/0x20
? do_user_addr_fault+0x6fd/0x740
? prb_read_valid+0x1d/0x30
? exc_page_fault+0x55/0xd0
? asm_exc_page_fault+0x2b/0x30
? splice_to_socket+0x52e/0x630
? shmem_file_splice_read+0x2b1/0x310
direct_splice_actor+0x47/0x70
splice_direct_to_actor+0x133/0x300
? do_splice_direct+0x90/0x90
do_splice_direct+0x64/0x90
? __ia32_sys_tee+0x30/0x30
do_sendfile+0x214/0x300
__se_sys_sendfile64+0x8e/0xb0
__x64_sys_sendfile64+0x25/0x30
x64_sys_call+0xb82/0x2840
do_syscall_64+0x75/0x110
entry_SYSCALL_64_after_hwframe+0x4b/0x53
This is caused by tcp_bpf_sendmsg() returning a larger value(12289) than
size (8192), which causes the while loop in splice_to_socket() to release
an uninitialized pipe buf.
The underlying cause is that this code assumes sk_msg_memcopy_from_iter()
will copy all bytes upon success but it actually might only copy part of
it.
This commit changes it to use the real copied bytes.
Signed-off-by: Levi Zim <rsworktech@outlook.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Björn Töpel <bjorn@kernel.org>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241130-tcp-bpf-sendmsg-v1-2-bae583d014f3@outlook.com
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_bpf.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 392678ae80f4..47f65b1b70ca 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -495,7 +495,7 @@ more_data: static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) { struct sk_msg tmp, *msg_tx = NULL; - int copied = 0, err = 0; + int copied = 0, err = 0, ret = 0; struct sk_psock *psock; long timeo; int flags; @@ -538,14 +538,14 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) copy = msg_tx->sg.size - osize; } - err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx, + ret = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx, copy); - if (err < 0) { + if (ret < 0) { sk_msg_trim(sk, msg_tx, osize); goto out_err; } - copied += copy; + copied += ret; if (psock->cork_bytes) { if (size > psock->cork_bytes) psock->cork_bytes = 0; |