From f6fadff33e8b09373eedf99822b89d9dd84545b8 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 11 Jun 2018 23:22:04 +0200 Subject: [PATCH] tls: fix NULL pointer dereference on poll While hacking on kTLS, I ran into the following panic from an unprivileged netserver / netperf TCP session: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 PGD 800000037f378067 P4D 800000037f378067 PUD 3c0e61067 PMD 0 Oops: 0010 [#1] SMP KASAN PTI CPU: 1 PID: 2289 Comm: netserver Not tainted 4.17.0+ #139 Hardware name: LENOVO 20FBCTO1WW/20FBCTO1WW, BIOS N1FET47W (1.21 ) 11/28/2016 RIP: 0010: (null) Code: Bad RIP value. RSP: 0018:ffff88036abcf740 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88036f5f6800 RCX: 1ffff1006debed26 RDX: ffff88036abcf920 RSI: ffff8803cb1a4f00 RDI: ffff8803c258c280 RBP: ffff8803c258c280 R08: ffff8803c258c280 R09: ffffed006f559d48 R10: ffff88037aacea43 R11: ffffed006f559d49 R12: ffff8803c258c280 R13: ffff8803cb1a4f20 R14: 00000000000000db R15: ffffffffc168a350 FS: 00007f7e631f4700(0000) GS:ffff8803d1c80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000003ccf64005 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? tls_sw_poll+0xa4/0x160 [tls] ? sock_poll+0x20a/0x680 ? do_select+0x77b/0x11a0 ? poll_schedule_timeout.constprop.12+0x130/0x130 ? pick_link+0xb00/0xb00 ? read_word_at_a_time+0x13/0x20 ? vfs_poll+0x270/0x270 ? deref_stack_reg+0xad/0xe0 ? __read_once_size_nocheck.constprop.6+0x10/0x10 [...] Debugging further, it turns out that calling into ctx->sk_poll() is invalid since sk_poll itself is NULL which was saved from the original TCP socket in order for tls_sw_poll() to invoke it. Looks like the recent conversion from poll to poll_mask callback started in 152524231023 ("net: add support for ->poll_mask in proto_ops") missed to eventually convert kTLS, too: TCP's ->poll was converted over to the ->poll_mask in commit 2c7d3dacebd4 ("net/tcp: convert to ->poll_mask") and therefore kTLS wrongly saved the ->poll old one which is now NULL. Convert kTLS over to use ->poll_mask instead. Also instead of POLLIN | POLLRDNORM use the proper EPOLLIN | EPOLLRDNORM bits as the case in tcp_poll_mask() as well that is mangled here. Fixes: 2c7d3dacebd4 ("net/tcp: convert to ->poll_mask") Signed-off-by: Daniel Borkmann Cc: Christoph Hellwig Cc: Dave Watson Tested-by: Dave Watson Signed-off-by: David S. Miller --- include/net/tls.h | 6 ++---- net/tls/tls_main.c | 2 +- net/tls/tls_sw.c | 19 +++++++++---------- 3 files changed, 12 insertions(+), 15 deletions(-) diff --git a/include/net/tls.h b/include/net/tls.h index 70c273777fe9..7f84ea3e217c 100644 --- a/include/net/tls.h +++ b/include/net/tls.h @@ -109,8 +109,7 @@ struct tls_sw_context_rx { struct strparser strp; void (*saved_data_ready)(struct sock *sk); - unsigned int (*sk_poll)(struct file *file, struct socket *sock, - struct poll_table_struct *wait); + __poll_t (*sk_poll_mask)(struct socket *sock, __poll_t events); struct sk_buff *recv_pkt; u8 control; bool decrypted; @@ -225,8 +224,7 @@ void tls_sw_free_resources_tx(struct sock *sk); void tls_sw_free_resources_rx(struct sock *sk); int tls_sw_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, int flags, int *addr_len); -unsigned int tls_sw_poll(struct file *file, struct socket *sock, - struct poll_table_struct *wait); +__poll_t tls_sw_poll_mask(struct socket *sock, __poll_t events); ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags); diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c index 301f22430469..a127d61e8af9 100644 --- a/net/tls/tls_main.c +++ b/net/tls/tls_main.c @@ -712,7 +712,7 @@ static int __init tls_register(void) build_protos(tls_prots[TLSV4], &tcp_prot); tls_sw_proto_ops = inet_stream_ops; - tls_sw_proto_ops.poll = tls_sw_poll; + tls_sw_proto_ops.poll_mask = tls_sw_poll_mask; tls_sw_proto_ops.splice_read = tls_sw_splice_read; #ifdef CONFIG_TLS_DEVICE diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 8ca57d01b18f..34895b7c132d 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -915,23 +915,22 @@ ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos, return copied ? : err; } -unsigned int tls_sw_poll(struct file *file, struct socket *sock, - struct poll_table_struct *wait) +__poll_t tls_sw_poll_mask(struct socket *sock, __poll_t events) { - unsigned int ret; struct sock *sk = sock->sk; struct tls_context *tls_ctx = tls_get_ctx(sk); struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx); + __poll_t mask; - /* Grab POLLOUT and POLLHUP from the underlying socket */ - ret = ctx->sk_poll(file, sock, wait); + /* Grab EPOLLOUT and EPOLLHUP from the underlying socket */ + mask = ctx->sk_poll_mask(sock, events); - /* Clear POLLIN bits, and set based on recv_pkt */ - ret &= ~(POLLIN | POLLRDNORM); + /* Clear EPOLLIN bits, and set based on recv_pkt */ + mask &= ~(EPOLLIN | EPOLLRDNORM); if (ctx->recv_pkt) - ret |= POLLIN | POLLRDNORM; + mask |= EPOLLIN | EPOLLRDNORM; - return ret; + return mask; } static int tls_read_size(struct strparser *strp, struct sk_buff *skb) @@ -1188,7 +1187,7 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx) sk->sk_data_ready = tls_data_ready; write_unlock_bh(&sk->sk_callback_lock); - sw_ctx_rx->sk_poll = sk->sk_socket->ops->poll; + sw_ctx_rx->sk_poll_mask = sk->sk_socket->ops->poll_mask; strp_check_rcv(&sw_ctx_rx->strp); }