{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43050","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-05-01T14:12:55.979Z","datePublished":"2026-05-01T14:15:44.542Z","dateUpdated":"2026-05-11T22:16:44.767Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T22:16:44.767Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix use-after-free in sock_def_readable()\n\nA race condition exists between lec_atm_close() setting priv->lecd\nto NULL and concurrent access to priv->lecd in send_to_lecd(),\nlec_handle_bridge(), and lec_atm_send(). When the socket is freed\nvia RCU while another thread is still using it, a use-after-free\noccurs in sock_def_readable() when accessing the socket's wait queue.\n\nThe root cause is that lec_atm_close() clears priv->lecd without\nany synchronization, while callers dereference priv->lecd without\nany protection against concurrent teardown.\n\nFix this by converting priv->lecd to an RCU-protected pointer:\n- Mark priv->lecd as __rcu in lec.h\n- Use rcu_assign_pointer() in lec_atm_close() and lecd_attach()\n  for safe pointer assignment\n- Use rcu_access_pointer() for NULL checks that do not dereference\n  the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and\n  lecd_attach()\n- Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(),\n  lec_handle_bridge() and lec_atm_send() to safely access lecd\n- Use rcu_assign_pointer() followed by synchronize_rcu() in\n  lec_atm_close() to ensure all readers have completed before\n  proceeding. This is safe since lec_atm_close() is called from\n  vcc_release() which holds lock_sock(), a sleeping lock.\n- Remove the manual sk_receive_queue drain from lec_atm_close()\n  since vcc_destroy_socket() already drains it after lec_atm_close()\n  returns.\n\nv2: Switch from spinlock + sock_hold/put approach to RCU to properly\n    fix the race. The v1 spinlock approach had two issues pointed out\n    by Eric Dumazet:\n    1. priv->lecd was still accessed directly after releasing the\n       lock instead of using a local copy.\n    2. The spinlock did not prevent packets being queued after\n       lec_atm_close() drains sk_receive_queue since timer and\n       workqueue paths bypass netif_stop_queue().\n\nNote: Syzbot patch testing was attempted but the test VM terminated\n    unexpectedly with \"Connection to localhost closed by remote host\",\n    likely due to a QEMU AHCI emulation issue unrelated to this fix.\n    Compile testing with \"make W=1 net/atm/lec.o\" passes cleanly."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/lec.c","net/atm/lec.h"],"versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"3e8b25f32f2f35549d03d77da030a24a45bdef5b","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"750a33f417f3d196b86375f8d9f8938bacf130fe","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"317843d5355062020649124eb4a0d7acbcc3f53e","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"b256d055da47258e63f8b40965f276c5f23d229a","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"3989740fa4978e1d2d51ecc62be1b01093e104ad","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"abc10f85a3965ac14b9ed7ad3e67b35604a63aa3","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"5fbbb1ff936d7ff9528d929c1549977e8123d8a8","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"922814879542c2e397b0e9641fd36b8202a8e555","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/lec.c","net/atm/lec.h"],"versions":[{"version":"2.6.12","status":"affected"},{"version":"0","lessThan":"2.6.12","status":"unaffected","versionType":"semver"},{"version":"5.10.253","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.203","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.168","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.134","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.81","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.22","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"6.19.12","lessThanOrEqual":"6.19.*","status":"unaffected","versionType":"semver"},{"version":"7.0","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.134"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.0"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/3e8b25f32f2f35549d03d77da030a24a45bdef5b"},{"url":"https://git.kernel.org/stable/c/750a33f417f3d196b86375f8d9f8938bacf130fe"},{"url":"https://git.kernel.org/stable/c/317843d5355062020649124eb4a0d7acbcc3f53e"},{"url":"https://git.kernel.org/stable/c/b256d055da47258e63f8b40965f276c5f23d229a"},{"url":"https://git.kernel.org/stable/c/3989740fa4978e1d2d51ecc62be1b01093e104ad"},{"url":"https://git.kernel.org/stable/c/abc10f85a3965ac14b9ed7ad3e67b35604a63aa3"},{"url":"https://git.kernel.org/stable/c/5fbbb1ff936d7ff9528d929c1549977e8123d8a8"},{"url":"https://git.kernel.org/stable/c/922814879542c2e397b0e9641fd36b8202a8e555"}],"title":"atm: lec: fix use-after-free in sock_def_readable()","x_generator":{"engine":"bippy-1.2.0"}}}}