{"id":"CVE-2026-31507","title":"net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer","summary":"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 …","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 7e8916f46c2f48607f907fd401590093753a6bc5","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < ae5575e660410c8d2c5d38fb28a0f37aea945676","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 98ba5cb274768146e25ffbfde47753652c1c20d3","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 81acbd345d405994875d419d43b319fee0b9ad62","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 7bcb974c771c863e8588cea0012ac204443a7126","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 54c87a730157868543ebdfa0ecb21b4590ed23a5","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 3cc76380fea749280c026f410af56a28aaac388a","Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 24dd586bb4cbba1889a50abe74143817a095c1c9","Linux 4.18"],"published":"2026-04-22","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:47:32.347Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31507","references":[{"url":"https://git.kernel.org/stable/c/7e8916f46c2f48607f907fd401590093753a6bc5"},{"url":"https://git.kernel.org/stable/c/ae5575e660410c8d2c5d38fb28a0f37aea945676"},{"url":"https://git.kernel.org/stable/c/98ba5cb274768146e25ffbfde47753652c1c20d3"},{"url":"https://git.kernel.org/stable/c/81acbd345d405994875d419d43b319fee0b9ad62"},{"url":"https://git.kernel.org/stable/c/7bcb974c771c863e8588cea0012ac204443a7126"},{"url":"https://git.kernel.org/stable/c/54c87a730157868543ebdfa0ecb21b4590ed23a5"},{"url":"https://git.kernel.org/stable/c/3cc76380fea749280c026f410af56a28aaac388a"},{"url":"https://git.kernel.org/stable/c/24dd586bb4cbba1889a50abe74143817a095c1c9"}],"tags":["cve.org"],"epss":0.00179,"epssPercentile":0.06564,"ingestedAt":"2026-09-08T15:33:26.990Z","slug":"CVE-2026-31507","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 7e8916f46c2f48607f907fd401590093753a6bc5`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < ae5575e660410c8d2c5d38fb28a0f37aea945676`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 98ba5cb274768146e25ffbfde47753652c1c20d3`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 81acbd345d405994875d419d43b319fee0b9ad62`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 7bcb974c771c863e8588cea0012ac204443a7126`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 54c87a730157868543ebdfa0ecb21b4590ed23a5`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 3cc76380fea749280c026f410af56a28aaac388a`\n- `Linux >= 9014db202cb764b8e14c53e7bacc81f9a1a2ba7f < 24dd586bb4cbba1889a50abe74143817a095c1c9`\n- `Linux 4.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}