{
  "threat_severity" : "Moderate",
  "public_date" : "2026-04-22T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer",
    "id" : "2460706",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2460706"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-911",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnet/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer\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 *.\nWhen both pipes are subsequently released, smc_rx_pipe_buf_release() is\ncalled twice against the same object:\n1st call: kfree(priv)  sock_put(sk)  smc_rx_update_cons()  [correct]\n2nd call: kfree(priv)  sock_put(sk)  smc_rx_update_cons()  [UAF]\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:\nBUG: KASAN: slab-use-after-free in smc_rx_pipe_buf_release+0x78/0x2a0\nRead of size 8 at addr ffff888004a45740 by task smc_splice_tee_/74\nCall Trace:\n<TASK>\ndump_stack_lvl+0x53/0x70\nprint_report+0xce/0x650\nkasan_report+0xc6/0x100\nsmc_rx_pipe_buf_release+0x78/0x2a0\nfree_pipe_info+0xd4/0x130\npipe_release+0x142/0x160\n__fput+0x1c6/0x490\n__x64_sys_close+0x4f/0x90\ndo_syscall_64+0xa6/0x1a0\nentry_SYSCALL_64_after_hwframe+0x77/0x7f\n</TASK>\nBUG: kernel NULL pointer dereference, address: 0000000000000020\nRIP: 0010:smc_rx_update_consumer+0x8d/0x350\nCall Trace:\n<TASK>\nsmc_rx_pipe_buf_release+0x121/0x2a0\nfree_pipe_info+0xd4/0x130\npipe_release+0x142/0x160\n__fput+0x1c6/0x490\n__x64_sys_close+0x4f/0x90\ndo_syscall_64+0xa6/0x1a0\nentry_SYSCALL_64_after_hwframe+0x77/0x7f\n</TASK>\nKernel panic - not syncing: Fatal exception\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.\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.", "A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SMC) module. A local user can exploit this vulnerability by using the tee(2) system call to duplicate a splice pipe buffer, leading to a double-free condition. This double-free can result in a use-after-free error and a kernel null pointer dereference, ultimately causing a kernel panic and a denial of service on the affected system." ],
  "statement" : "Upstream rejects `tee()`/`splice_pipe_to_pipe()` paths that would duplicate SMC pipe buffers because refcounting alone cannot fix receive-window accounting. Red Hat advises patched kernels for SMC users. Unload `smc` where the protocol is unused.",
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-31507\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31507\nhttps://lore.kernel.org/linux-cve-announce/2026042207-CVE-2026-31507-cbc0@gregkh/T" ],
  "name" : "CVE-2026-31507",
  "mitigation" : {
    "value" : "To mitigate this issue, prevent the smc module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.",
    "lang" : "en:us"
  },
  "csaw" : false
}