From 3709b9a67cdd88761a540b32a1f89007f0e1b5b3 Mon Sep 17 00:00:00 2001

From: Ryan Sullivan <rysulliv@redhat.com>

Date: Tue, 20 Feb 2024 13:30:50 -0500

Subject: [KPATCH CVE-2023-4622] kpatch fixes for CVE-2023-4622

Kernels:

3.10.0-1160.99.1.el7

3.10.0-1160.102.1.el7

3.10.0-1160.105.1.el7

3.10.0-1160.108.1.el7

Kpatch-MR: https://gitlab.com/redhat/prdsc/rhel/src/kpatch/rhel-7/-/merge_requests/68

Approved-by: Joe Lawrence (@joe.lawrence)

Changes since last build:

[x86_64]:

af_unix.o: changed function: unix_stream_sendpage

sch_hfsc.o: changed function: hfsc_change_class

[ppc64le]:

af_unix.o: changed function: unix_stream_sendpage

---------------------------

Modifications: none

commit 5697266978cafba4a0784a2bc81588abeb3d94a8

Author: Guillaume Nault <gnault@redhat.com>

Date:   Wed Jan 31 13:11:14 2024 +0100

    af_unix: Fix null-ptr-deref in unix_stream_sendpage().

    JIRA: https://issues.redhat.com/browse/RHEL-16144

    Upstream Status: git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    CVE: CVE-2023-4622

    commit 790c2f9d15b594350ae9bca7b236f2b1859de02c

    Author: Kuniyuki Iwashima <kuniyu@amazon.com>

    Date:   Mon Aug 21 10:55:05 2023 -0700

        af_unix: Fix null-ptr-deref in unix_stream_sendpage().

        Bing-Jhong Billy Jheng reported null-ptr-deref in unix_stream_sendpage()

        with detailed analysis and a nice repro.

        unix_stream_sendpage() tries to add data to the last skb in the peer's

        recv queue without locking the queue.

        If the peer's FD is passed to another socket and the socket's FD is

        passed to the peer, there is a loop between them.  If we close both

        sockets without receiving FD, the sockets will be cleaned up by garbage

        collection.

        The garbage collection iterates such sockets and unlinks skb with

        FD from the socket's receive queue under the queue's lock.

        So, there is a race where unix_stream_sendpage() could access an skb

        locklessly that is being released by garbage collection, resulting in

        use-after-free.

        To avoid the issue, unix_stream_sendpage() must lock the peer's recv

        queue.

        Note the issue does not exist in 6.5+ thanks to the recent sendpage()

        refactoring.

        This patch is originally written by Linus Torvalds.

        BUG: unable to handle page fault for address: ffff988004dd6870

        PF: supervisor read access in kernel mode

        PF: error_code(0x0000) - not-present page

        PGD 0 P4D 0

        PREEMPT SMP PTI

        CPU: 4 PID: 297 Comm: garbage_uaf Not tainted 6.1.46 #1

        Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014

        RIP: 0010:kmem_cache_alloc_node+0xa2/0x1e0

        Code: c0 0f 84 32 01 00 00 41 83 fd ff 74 10 48 8b 00 48 c1 e8 3a 41 39 c5 0f 85 1c 01 00 00 41 8b 44 24 28 49 8b 3c 24 48 8d 4a 40 <49> 8b 1c 06 4c 89 f0 65 48 0f c7 0f 0f 94 c0 84 c0 74 a1 41 8b 44

        RSP: 0018:ffffc9000079fac0 EFLAGS: 00000246

        RAX: 0000000000000070 RBX: 0000000000000005 RCX: 000000000001a284

        RDX: 000000000001a244 RSI: 0000000000400cc0 RDI: 000000000002eee0

        RBP: 0000000000400cc0 R08: 0000000000400cc0 R09: 0000000000000003

        R10: 0000000000000001 R11: 0000000000000000 R12: ffff888003970f00

        R13: 00000000ffffffff R14: ffff988004dd6800 R15: 00000000000000e8

        FS:  00007f174d6f3600(0000) GS:ffff88807db00000(0000) knlGS:0000000000000000

        CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033

        CR2: ffff988004dd6870 CR3: 00000000092be000 CR4: 00000000007506e0

        PKRU: 55555554

        Call Trace:

         <TASK>

         ? __die_body.cold+0x1a/0x1f

         ? page_fault_oops+0xa9/0x1e0

         ? fixup_exception+0x1d/0x310

         ? exc_page_fault+0xa8/0x150

         ? asm_exc_page_fault+0x22/0x30

         ? kmem_cache_alloc_node+0xa2/0x1e0

         ? __alloc_skb+0x16c/0x1e0

         __alloc_skb+0x16c/0x1e0

         alloc_skb_with_frags+0x48/0x1e0

         sock_alloc_send_pskb+0x234/0x270

         unix_stream_sendmsg+0x1f5/0x690

         sock_sendmsg+0x5d/0x60

         ____sys_sendmsg+0x210/0x260

         ___sys_sendmsg+0x83/0xd0

         ? kmem_cache_alloc+0xc6/0x1c0

         ? avc_disable+0x20/0x20

         ? percpu_counter_add_batch+0x53/0xc0

         ? alloc_empty_file+0x5d/0xb0

         ? alloc_file+0x91/0x170

         ? alloc_file_pseudo+0x94/0x100

         ? __fget_light+0x9f/0x120

         __sys_sendmsg+0x54/0xa0

         do_syscall_64+0x3b/0x90

         entry_SYSCALL_64_after_hwframe+0x69/0xd3

        RIP: 0033:0x7f174d639a7d

        Code: 28 89 54 24 1c 48 89 74 24 10 89 7c 24 08 e8 8a c1 f4 ff 8b 54 24 1c 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 33 44 89 c7 48 89 44 24 08 e8 de c1 f4 ff 48

        RSP: 002b:00007ffcb563ea50 EFLAGS: 00000293 ORIG_RAX: 000000000000002e

        RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f174d639a7d

        RDX: 0000000000000000 RSI: 00007ffcb563eab0 RDI: 0000000000000007

        RBP: 00007ffcb563eb10 R08: 0000000000000000 R09: 00000000ffffffff

        R10: 00000000004040a0 R11: 0000000000000293 R12: 00007ffcb563ec28

        R13: 0000000000401398 R14: 0000000000403e00 R15: 00007f174d72c000

         </TASK>

        Fixes: 869e7c62486e ("net: af_unix: implement stream sendpage support")

        Reported-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>

        Reviewed-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>

        Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>

        Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

        Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>

        Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    Signed-off-by: Guillaume Nault <gnault@redhat.com>

Signed-off-by: Ryan Sullivan <rysulliv@redhat.com>

---

 net/unix/af_unix.c | 9 ++++-----

 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c

index a264b4598872..033986a95c3d 100644

--- a/net/unix/af_unix.c

+++ b/net/unix/af_unix.c

@@ -1960,6 +1960,7 @@ static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,

 	if (false) {

 alloc_skb:

+		spin_unlock(&other->sk_receive_queue.lock);

 		unix_state_unlock(other);

 		mutex_unlock(&unix_sk(other)->iolock);

 		newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,

@@ -1999,6 +2000,7 @@ alloc_skb:

 		init_scm = false;

 	}

+	spin_lock(&other->sk_receive_queue.lock);

 	skb = skb_peek_tail(&other->sk_receive_queue);

 	if (tail && tail == skb) {

 		skb = newskb;

@@ -2029,14 +2031,11 @@ alloc_skb:

 	atomic_add(size, &sk->sk_wmem_alloc);

 	if (newskb) {

-		err = unix_scm_to_skb(&scm, skb, false);

-		if (err)

-			goto err_state_unlock;

-		spin_lock(&other->sk_receive_queue.lock);

+		unix_scm_to_skb(&scm, skb, false);

 		__skb_queue_tail(&other->sk_receive_queue, newskb);

-		spin_unlock(&other->sk_receive_queue.lock);

 	}

+	spin_unlock(&other->sk_receive_queue.lock);

 	unix_state_unlock(other);

 	mutex_unlock(&unix_sk(other)->iolock);

-- 

2.44.0