In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Fix UAF in svc_tcp_listen_data_ready()
After the listener svc_sock is freed, and before invoking svc_tcp_accept()
for the established child sock, there is a window that the newsock
retaining a freed listener svc_sock in sk_user_data which cloning from
parent. In the race window, if data is received on the newsock, we will
observe use-after-free report in svc_tcp_listen_data_ready().
Reproduce by two tasks:
KASAN report:
==================================================================
BUG: KASAN: slab-use-after-free in svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]
Read of size 8 at addr ffff888139d96228 by task nc/102553
CPU: 7 PID: 102553 Comm: nc Not tainted 6.3.0+ #18
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
Call Trace:
<IRQ>
dump_stack_lvl+0x33/0x50
print_address_description.constprop.0+0x27/0x310
print_report+0x3e/0x70
kasan_report+0xae/0xe0
svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]
tcp_data_queue+0x9f4/0x20e0
tcp_rcv_established+0x666/0x1f60
tcp_v4_do_rcv+0x51c/0x850
tcp_v4_rcv+0x23fc/0x2e80
ip_protocol_deliver_rcu+0x62/0x300
ip_local_deliver_finish+0x267/0x350
ip_local_deliver+0x18b/0x2d0
ip_rcv+0x2fb/0x370
__netif_receive_skb_one_core+0x166/0x1b0
process_backlog+0x24c/0x5e0
__napi_poll+0xa2/0x500
net_rx_action+0x854/0xc90
__do_softirq+0x1bb/0x5de
do_softirq+0xcb/0x100
</IRQ>
<TASK>
…
</TASK>
Allocated by task 102371:
kasan_save_stack+0x1e/0x40
kasan_set_track+0x21/0x30
__kasan_kmalloc+0x7b/0x90
svc_setup_socket+0x52/0x4f0 [sunrpc]
svc_addsock+0x20d/0x400 [sunrpc]
__write_ports_addfd+0x209/0x390 [nfsd]
write_ports+0x239/0x2c0 [nfsd]
nfsctl_transaction_write+0xac/0x110 [nfsd]
vfs_write+0x1c3/0xae0
ksys_write+0xed/0x1c0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
Freed by task 102551:
kasan_save_stack+0x1e/0x40
kasan_set_track+0x21/0x30
kasan_save_free_info+0x2a/0x50
__kasan_slab_free+0x106/0x190
__kmem_cache_free+0x133/0x270
svc_xprt_free+0x1e2/0x350 [sunrpc]
svc_xprt_destroy_all+0x25a/0x440 [sunrpc]
nfsd_put+0x125/0x240 [nfsd]
nfsd_svc+0x2cb/0x3c0 [nfsd]
write_threads+0x1ac/0x2a0 [nfsd]
nfsctl_transaction_write+0xac/0x110 [nfsd]
vfs_write+0x1c3/0xae0
ksys_write+0xed/0x1c0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
Fix the UAF by simply doing nothing in svc_tcp_listen_data_ready()
if state != TCP_LISTEN, that will avoid dereferencing svsk for all
child socket.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/sunrpc/svcsock.c"
],
"versions": [
{
"version": "fa9251afc33c",
"lessThan": "c7b8c2d06e43",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "dfc896c4a75c",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "42725e5c1b18",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "cd5ec3ee52ce",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "fbf4ace39b2e",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "ef047411887f",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "7e1f98905562",
"status": "affected",
"versionType": "git"
},
{
"version": "fa9251afc33c",
"lessThan": "fc80fc2d4e39",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/sunrpc/svcsock.c"
],
"versions": [
{
"version": "4.8",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.8",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.14.322",
"lessThanOrEqual": "4.14.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "4.19.291",
"lessThanOrEqual": "4.19.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.4.251",
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.10.188",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.15.121",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.39",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.4.4",
"lessThanOrEqual": "6.4.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.5",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]
git.kernel.org/stable/c/42725e5c1b181b757ba11d804443922982334d9b
git.kernel.org/stable/c/7e1f989055622fd086c5dfb291fc72adf5660b6f
git.kernel.org/stable/c/c7b8c2d06e437639694abe76978e915cfb73f428
git.kernel.org/stable/c/cd5ec3ee52ce4b7e283cc11facfa420c297c8065
git.kernel.org/stable/c/dfc896c4a75cb8cd7cb2dfd9b469cf1e3f004254
git.kernel.org/stable/c/ef047411887ff0845afd642d6a687819308e1a4e
git.kernel.org/stable/c/fbf4ace39b2e4f3833236afbb2336edbafd75eee
git.kernel.org/stable/c/fc80fc2d4e39137869da3150ee169b40bf879287