{"id":"CVE-2024-37356","revision":"f6178b50c0544533b7b631342e36d5ac","records":[{"revision":"f6178b50c0544533b7b631342e36d5ac","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2024-37356","aliases":[],"title":"tcp: Fix shift-out-of-bounds in dctcp_update_alpha().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Fix shift-out-of-bounds in dctcp_update_alpha().\n\nIn dctcp_update_alpha(), we use a module parameter dctcp_shift_g\nas follows:\n\n alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);\n ...\n delivered_ce <<= (10 - dctcp_shift_g);\n\nIt seems syzkaller started fuzzing module parameters and triggered\nshift-out-of-bounds [0] by setting 100 to dctcp_shift_g:\n\n memcpy((void*)0x20000080,\n \"/sys/module/tcp_dctcp/parameters/dctcp_shift_g\\000\", 47);\n res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20000080ul,\n /*flags=*/2ul, /*mode=*/0ul);\n memcpy((void*)0x20000000, \"100\\000\", 4);\n syscall(__NR_write, /*fd=*/r[0], /*val=*/0x20000000ul, /*len=*/4ul);\n\nLet's limit the max value of dctcp_shift_g by param_set_uint_minmax().\n\nWith this patch:\n\n # echo 10 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g\n # cat /sys/module/tcp_dctcp/parameters/dctcp_shift_g\n 10\n # echo 11 > /sys/module/tcp_dctcp/parameters/dctcp_shift_g\n -bash: echo: write error: Invalid argument\n\n[0]:\nUBSAN: shift-out-of-bounds in net/ipv4/tcp_dctcp.c:143:12\nshift exponent 100 is too large for 32-bit type 'u32' (aka 'unsigned int')\nCPU: 0 PID: 8083 Comm: syz-executor345 Not tainted 6.9.0-05151-g1b294a1f3561 #2\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.13.0-1ubuntu1.1 04/01/2014\nCall Trace:\n \n __dump_stack lib/dump_stack.c:88 [inline]\n dump_stack_lvl+0x201/0x300 lib/dump_stack.c:114\n ubsan_epilogue lib/ubsan.c:231 [inline]\n __ubsan_handle_shift_out_of_bounds+0x346/0x3a0 lib/ubsan.c:468\n dctcp_update_alpha+0x540/0x570 net/ipv4/tcp_dctcp.c:143\n tcp_in_ack_event net/ipv4/tcp_input.c:3802 [inline]\n tcp_ack+0x17b1/0x3bc0 net/ipv4/tcp_input.c:3948\n tcp_rcv_state_process+0x57a/0x2290 net/ipv4/tcp_input.c:6711\n tcp_v4_do_rcv+0x764/0xc40 net/ipv4/tcp_ipv4.c:1937\n sk_backlog_rcv include/net/sock.h:1106 [inline]\n __release_sock+0x20f/0x350 net/core/sock.c:2983\n release_sock+0x61/0x1f0 net/core/sock.c:3549\n mptcp_subflow_shutdown+0x3d0/0x620 net/mptcp/protocol.c:2907\n mptcp_check_send_data_fin+0x225/0x410 net/mptcp/protocol.c:2976\n __mptcp_close+0x238/0xad0 net/mptcp/protocol.c:3072\n mptcp_close+0x2a/0x1a0 net/mptcp/protocol.c:3127\n inet_release+0x190/0x1f0 net/ipv4/af_inet.c:437\n __sock_release net/socket.c:659 [inline]\n sock_close+0xc0/0x240 net/socket.c:1421\n __fput+0x41b/0x890 fs/file_table.c:422\n task_work_run+0x23b/0x300 kernel/task_work.c:180\n exit_task_work include/linux/task_work.h:38 [inline]\n do_exit+0x9c8/0x2540 kernel/exit.c:878\n do_group_exit+0x201/0x2b0 kernel/exit.c:1027\n __do_sys_exit_group kernel/exit.c:1038 [inline]\n __se_sys_exit_group kernel/exit.c:1036 [inline]\n __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xe4/0x240 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x67/0x6f\nRIP: 0033:0x7f6c2b5005b6\nCode: Unable to access opcode bytes at 0x7f6c2b50058c.\nRSP: 002b:00007ffe883eb948 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7\nRAX: ffffffffffffffda RBX: 00007f6c2b5862f0 RCX: 00007f6c2b5005b6\nRDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001\nRBP: 0000000000000001 R08: 00000000000000e7 R09: ffffffffffffffc0\nR10: 0000000000000006 R11: 0000000000000246 R12: 00007f6c2b5862f0\nR13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001\n ","state":0,"publishedAt":"2024-06-21T10:18:11.642+00:00","modifiedAt":"2026-10-15T00:43:14.41+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ipv4/tcp_dctcp.c\"\n ],\n \"versions\": [\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"06d0fe049b51b0a92a70df8333fd85c4ba3eb2c6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"6aacaa80d962f4916ccf90e2080306cec6c90fcf\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"e9b2f60636d18dfd0dd4965b3316f88dfd6a2b31\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"8602150286a2a860a1dc55cbd04f99316f19b40a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"e65d13ec00a738fa7661925fd5929ab3c765d4be\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"02261d3f9dc7d1d7be7d778f839e3404ab99034c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"237340dee373b97833a491d2e99fcf1d4a9adafd\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"e3118e8359bb7c59555aca60c725106e6d78c5ce\",\n \"lessThan\": \"3ebc46ca8675de6378e3f8f40768e180bb8afa66\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ipv4/tcp_dctcp.c\"\n ],\n \"versions\": [\n {\n \"version\": \"3.18\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"3.18\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"4.19.316\",\n \"lessThanOrEqual\": \"4.19.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.278\",\n \"lessThanOrEqual\": \"5.4.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.219\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.161\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.93\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.33\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.9.4\",\n \"lessThanOrEqual\": \"6.9.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.10\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/06d0fe049b51b0a92a70df8333fd85c4ba3eb2c6","https://git.kernel.org/stable/c/6aacaa80d962f4916ccf90e2080306cec6c90fcf","https://git.kernel.org/stable/c/e9b2f60636d18dfd0dd4965b3316f88dfd6a2b31","https://git.kernel.org/stable/c/8602150286a2a860a1dc55cbd04f99316f19b40a","https://git.kernel.org/stable/c/e65d13ec00a738fa7661925fd5929ab3c765d4be","https://git.kernel.org/stable/c/02261d3f9dc7d1d7be7d778f839e3404ab99034c","https://git.kernel.org/stable/c/237340dee373b97833a491d2e99fcf1d4a9adafd","https://git.kernel.org/stable/c/3ebc46ca8675de6378e3f8f40768e180bb8afa66"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2024-37356","license":"CVE Program Terms of Use","key":"cve-program:CVE-2024-37356","identifiers":["CVE-2024-37356"]},"retained":false,"historicalAffected":[]}],"coverage":[]}