CVE-2024-26731

EPSS 0.03%
Published 03.04.2024 17:15:50
Last modified 03.04.2025 17:09:12
Source 416baaa9-dc9f-4396-8d5f-8c081f
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In the Linux kernel, the following vulnerability has been resolved:

bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready()

syzbot reported the following NULL pointer dereference issue [1]:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  [...]
  RIP: 0010:0x0
  [...]
  Call Trace:
   <TASK>
   sk_psock_verdict_data_ready+0x232/0x340 net/core/skmsg.c:1230
   unix_stream_sendmsg+0x9b4/0x1230 net/unix/af_unix.c:2293
   sock_sendmsg_nosec net/socket.c:730 [inline]
   __sock_sendmsg+0x221/0x270 net/socket.c:745
   ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
   ___sys_sendmsg net/socket.c:2638 [inline]
   __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667
   do_syscall_64+0xf9/0x240
   entry_SYSCALL_64_after_hwframe+0x6f/0x77

If sk_psock_verdict_data_ready() and sk_psock_stop_verdict() are called
concurrently, psock->saved_data_ready can be NULL, causing the above issue.

This patch fixes this issue by calling the appropriate data ready function
using the sk_psock_data_ready() helper and protecting it from concurrency
with sk->sk_callback_lock.