CVE-2024-40954

In the Linux kernel, the following vulnerability has been resolved:
net: do not leave a dangling sk pointer, when socket creation fails
It is possible to trigger a use-after-free by:

• attaching an fentry probe to __sock_release() and the probe calling the
  bpf_get_socket_cookie() helper
• running traceroute -I 1.1.1.1 on a freshly booted VM
  A KASAN enabled kernel will log something like below (decoded and
  stripped):
  ==================================================================
  BUG: KASAN: slab-use-after-free in __sock_gen_cookie
  (./arch/x86/include/asm/atomic64_64.h:15
  ./include/linux/atomic/atomic-arch-fallback.h:2583
  ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
  Read of size 8 at addr ffff888007110dd8 by task traceroute/299
  CPU: 2 PID: 299 Comm: traceroute Tainted: G E 6.10.0-rc2+
  #2
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
  1.16.2-debian-1.16.2-1 04/01/2014
  Call Trace:
  <TASK>
  dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1))
  print_report (mm/kasan/report.c:378 mm/kasan/report.c:488)
  ? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15
  ./include/linux/atomic/atomic-arch-fallback.h:2583
  ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
  kasan_report (mm/kasan/report.c:603)
  ? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15
  ./include/linux/atomic/atomic-arch-fallback.h:2583
  ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
  kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189)
  __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15
  ./include/linux/atomic/atomic-arch-fallback.h:2583
  ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
  bpf_get_socket_ptr_cookie (./arch/x86/include/asm/preempt.h:94
  ./include/linux/sock_diag.h:42 net/core/filter.c:5094
  net/core/filter.c:5092)
  bpf_prog_875642cf11f1d139___sock_release+0x6e/0x8e
  bpf_trampoline_6442506592+0x47/0xaf
  __sock_release (net/socket.c:652)
  __sock_create (net/socket.c:1601)
  …
  Allocated by task 299 on cpu 2 at 78.328492s:
  kasan_save_stack (mm/kasan/common.c:48)
  kasan_save_track (mm/kasan/common.c:68)
  __kasan_slab_alloc (mm/kasan/common.c:312 mm/kasan/common.c:338)
  kmem_cache_alloc_noprof (mm/slub.c:3941 mm/slub.c:4000 mm/slub.c:4007)
  sk_prot_alloc (net/core/sock.c:2075)
  sk_alloc (net/core/sock.c:2134)
  inet_create (net/ipv4/af_inet.c:327 net/ipv4/af_inet.c:252)
  __sock_create (net/socket.c:1572)
  __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
  __x64_sys_socket (net/socket.c:1718)
  do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
  Freed by task 299 on cpu 2 at 78.328502s:
  kasan_save_stack (mm/kasan/common.c:48)
  kasan_save_track (mm/kasan/common.c:68)
  kasan_save_free_info (mm/kasan/generic.c:582)
  poison_slab_object (mm/kasan/common.c:242)
  __kasan_slab_free (mm/kasan/common.c:256)
  kmem_cache_free (mm/slub.c:4437 mm/slub.c:4511)
  __sk_destruct (net/core/sock.c:2117 net/core/sock.c:2208)
  inet_create (net/ipv4/af_inet.c:397 net/ipv4/af_inet.c:252)
  __sock_create (net/socket.c:1572)
  __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
  __x64_sys_socket (net/socket.c:1718)
  do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
  Fix this by clearing the struct socket reference in sk_common_release() to
  cover
  all protocol families create functions, which may already attached the
  reference to the sk object with sock_init_data().