PT-2026-51899 · Linux · Linux
Published
2026-06-24
·
Updated
2026-06-24
·
CVE-2026-53005
None
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In the Linux kernel, the following vulnerability has been resolved:
af unix: Drop all SCM attributes for SOCKMAP.
SOCKMAP can hide inflight fd from AF UNIX GC.
When a socket in SOCKMAP receives skb with inflight fd,
sk psock verdict data ready() looks up the mapped socket and
enqueue skb to its psock->ingress skb.
Since neither the old nor the new GC can inspect the psock
queue, the hidden skb leaks the inflight sockets. Note that
this cannot be detected via kmemleak because inflight sockets
are linked to a global list.
In addition, SOCKMAP redirect breaks the Tarjan-based GC's
assumption that unix edge.successor is always alive, which
is no longer true once skb is redirected, resulting in
use-after-free below. [0]
Moreover, SOCKMAP does not call scm stat del() properly,
so unix show fdinfo() could report an incorrect fd count.
sk msg recvmsg() does not support any SCM attributes in the
first place.
Let's drop all SCM attributes before passing skb to the
SOCKMAP layer.
[0]:
BUG: KASAN: slab-use-after-free in unix del edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251)
Read of size 8 at addr ffff888125362670 by task kworker/56:1/496
CPU: 56 UID: 0 PID: 496 Comm: kworker/56:1 Not tainted 7.0.0-rc7-00263-gb9d8b856689d #3 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Workqueue: events sk psock backlog
Call Trace:
dump stack lvl (lib/dump stack.c:122)
print report (mm/kasan/report.c:379)
kasan report (mm/kasan/report.c:597)
unix del edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251)
unix destroy fpl (net/unix/garbage.c:317)
unix destruct scm (./include/net/scm.h:80 ./include/net/scm.h:86 net/unix/af unix.c:1976)
sk psock backlog (./include/linux/skbuff.h:?)
process scheduled works (kernel/workqueue.c:?)
worker thread (kernel/workqueue.c:?)
kthread (kernel/kthread.c:438)
ret from fork (arch/x86/kernel/process.c:164)
ret from fork asm (arch/x86/entry/entry 64.S:258)
Allocated by task 955:
kasan save track (mm/kasan/common.c:58 mm/kasan/common.c:78)
kasan slab alloc (mm/kasan/common.c:369)
kmem cache alloc noprof (mm/slub.c:4539)
sk prot alloc (net/core/sock.c:2240)
sk alloc (net/core/sock.c:2301)
unix create1 (net/unix/af unix.c:1099)
unix create (net/unix/af unix.c:1169)
sock create (net/socket.c:1606)
sys socketpair (net/socket.c:1811)
x64 sys socketpair (net/socket.c:1863 net/socket.c:1860 net/socket.c:1860)
do syscall 64 (arch/x86/entry/syscall 64.c:?)
entry SYSCALL 64 after hwframe (arch/x86/entry/entry 64.S:130)
Freed by task 496:
kasan save track (mm/kasan/common.c:58 mm/kasan/common.c:78)
kasan save free info (mm/kasan/generic.c:587)
kasan slab free (mm/kasan/common.c:287)
kmem cache free (mm/slub.c:6165)
sk destruct (net/core/sock.c:2282 net/core/sock.c:2384)
sk psock destroy (./include/net/sock.h:?)
process scheduled works (kernel/workqueue.c:?)
worker thread (kernel/workqueue.c:?)
kthread (kernel/kthread.c:438)
ret from fork (arch/x86/kernel/process.c:164)
ret from fork asm (arch/x86/entry/entry 64.S:258)
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Related Identifiers
Affected Products
Linux