From: Levi Zim <rsworktech@outlook.com> mainline inclusion from mainline-v6.13-rc3 commit 5153a75ef34b3f7478ca918044d0f05eed8fb3f9 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8376 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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@outlo... Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/ipv4/tcp_bpf.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index dc8cbee30cfd..0e56f3baf98a 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -498,7 +498,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, 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; @@ -541,14 +541,14 @@ 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; -- 2.25.1