{"id":"CVE-2026-31507","summary":"net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer","details":"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-\u003esmc 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   \u003cTASK\u003e\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   \u003c/TASK\u003e\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000020\n  RIP: 0010:smc_rx_update_consumer+0x8d/0x350\n  Call Trace:\n   \u003cTASK\u003e\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   \u003c/TASK\u003e\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.","modified":"2026-05-28T03:55:53.590258397Z","published":"2026-04-22T13:54:25.910Z","related":["SUSE-SU-2026:2068-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31507.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/24dd586bb4cbba1889a50abe74143817a095c1c9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3cc76380fea749280c026f410af56a28aaac388a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/54c87a730157868543ebdfa0ecb21b4590ed23a5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7bcb974c771c863e8588cea0012ac204443a7126"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7e8916f46c2f48607f907fd401590093753a6bc5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/81acbd345d405994875d419d43b319fee0b9ad62"},{"type":"WEB","url":"https://git.kernel.org/stable/c/98ba5cb274768146e25ffbfde47753652c1c20d3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ae5575e660410c8d2c5d38fb28a0f37aea945676"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31507.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31507"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9014db202cb764b8e14c53e7bacc81f9a1a2ba7f"},{"fixed":"7e8916f46c2f48607f907fd401590093753a6bc5"},{"fixed":"ae5575e660410c8d2c5d38fb28a0f37aea945676"},{"fixed":"98ba5cb274768146e25ffbfde47753652c1c20d3"},{"fixed":"81acbd345d405994875d419d43b319fee0b9ad62"},{"fixed":"7bcb974c771c863e8588cea0012ac204443a7126"},{"fixed":"54c87a730157868543ebdfa0ecb21b4590ed23a5"},{"fixed":"3cc76380fea749280c026f410af56a28aaac388a"},{"fixed":"24dd586bb4cbba1889a50abe74143817a095c1c9"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31507.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.18.0"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.131"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31507.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}