{
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        "cveId": "CVE-2026-31507",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-03-09T15:48:24.106Z",
        "datePublished": "2026-04-22T13:54:25.910Z",
        "dateUpdated": "2026-08-05T12:23:09.141Z"
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                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer\n\nsmc_rx_splice() allocates one smc_spd_priv per pipe_buffer and stores\nthe pointer in pipe_buffer.private.  The pipe_buf_operations for these\nbuffers used .get = generic_pipe_buf_get, which only increments the page\nreference count when tee(2) duplicates a pipe buffer.  The smc_spd_priv\npointer itself was not handled, so after tee() both the original and the\ncloned pipe_buffer share the same smc_spd_priv *.\n\nWhen both pipes are subsequently released, smc_rx_pipe_buf_release() is\ncalled twice against the same object:\n\n  1st call: kfree(priv)  sock_put(sk)  smc_rx_update_cons()  [correct]\n  2nd call: kfree(priv)  sock_put(sk)  smc_rx_update_cons()  [UAF]\n\nKASAN reports a slab-use-after-free in smc_rx_pipe_buf_release(), which\nthen escalates to a NULL-pointer dereference and kernel panic via\nsmc_rx_update_consumer() when it chases the freed priv->smc pointer:\n\n  BUG: KASAN: slab-use-after-free in smc_rx_pipe_buf_release+0x78/0x2a0\n  Read of size 8 at addr ffff888004a45740 by task smc_splice_tee_/74\n  Call Trace:\n   <TASK>\n   dump_stack_lvl+0x53/0x70\n   print_report+0xce/0x650\n   kasan_report+0xc6/0x100\n   smc_rx_pipe_buf_release+0x78/0x2a0\n   free_pipe_info+0xd4/0x130\n   pipe_release+0x142/0x160\n   __fput+0x1c6/0x490\n   __x64_sys_close+0x4f/0x90\n   do_syscall_64+0xa6/0x1a0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   </TASK>\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000020\n  RIP: 0010:smc_rx_update_consumer+0x8d/0x350\n  Call Trace:\n   <TASK>\n   smc_rx_pipe_buf_release+0x121/0x2a0\n   free_pipe_info+0xd4/0x130\n   pipe_release+0x142/0x160\n   __fput+0x1c6/0x490\n   __x64_sys_close+0x4f/0x90\n   do_syscall_64+0xa6/0x1a0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   </TASK>\n  Kernel panic - not syncing: Fatal exception\n\nBeyond the memory-safety problem, duplicating an SMC splice buffer is\nsemantically questionable: smc_rx_update_cons() would advance the\nconsumer cursor twice for the same data, corrupting receive-window\naccounting.  A refcount on smc_spd_priv could fix the double-free, but\nthe cursor-accounting issue would still need to be addressed separately.\n\nThe .get callback is invoked by both tee(2) and splice_pipe_to_pipe()\nfor partial transfers; both will now return -EFAULT.  Users who need\nto duplicate SMC socket data must use a copy-based read path."
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                        "baseScore": 7.8,
                        "baseSeverity": "HIGH"
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                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "AV:L - The vulnerable path requires a local process to create or use an established non-fallback SMC socket, splice data from it into a pipe, and then duplicate that pipe buffer with tee(2) or partial pipe-to-pipe splice. A remote SMC peer can supply data, but cannot by itself invoke the required local splice/tee pipe-buffer operations.\nAC:L - There is no race or fragile timing requirement; once SMC data is available, the attacker-controlled syscall sequence deterministically creates two pipe buffers sharing the same smc_spd_priv. SMC-capable hardware/configuration is an affected deployment condition, not an exploitation race.\nPR:L - Creating SMC stream sockets and invoking splice(2), tee(2), pipe(2), and close(2) do not require CAP_NET_ADMIN or other elevated privileges. The attacker needs only basic local code execution.\nUI:N - No victim action is needed once the attacker has local execution; the attacker can perform the full syscall sequence and close both pipes. Any remote peer data needed for the SMC receive buffer can be generated by attacker-controlled endpoints in a plausible deployment.\nS:U - The vulnerability corrupts kernel memory in the same operating-system security authority as the vulnerable SMC/socket/pipe code. It is a standard kernel memory corruption issue, not a VM escape or cross-authority boundary bypass.\nC:H - The bug is a use-after-free/double-free of a heap object containing a kernel pointer and length, and the freed object is dereferenced on the second pipe-buffer release. Following kernel CVSS guidance, this memory corruption can support information disclosure primitives.\nI:H - The duplicate release can lead to allocator corruption and attacker-influenced dereferences through the freed smc_spd_priv contents. Following kernel CVSS guidance for UAF/double-free memory corruption, arbitrary write or control-flow compromise is a defensible impact.\nA:H - The reported failure includes KASAN slab-use-after-free followed by NULL pointer dereference and kernel panic in smc_rx_update_consumer(). Even without full exploitation, the sequence can crash the kernel."
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