{"id":"DEBIAN-CVE-2024-42240","details":"In the Linux kernel, the following vulnerability has been resolved:  x86/bhi: Avoid warning in #DB handler due to BHI mitigation  When BHI mitigation is enabled, if SYSENTER is invoked with the TF flag set then entry_SYSENTER_compat() uses CLEAR_BRANCH_HISTORY and calls the clear_bhb_loop() before the TF flag is cleared. This causes the #DB handler (exc_debug_kernel()) to issue a warning because single-step is used outside the entry_SYSENTER_compat() function.  To address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORY after making sure the TF flag is cleared.  The problem can be reproduced with the following sequence:    $ cat sysenter_step.c   int main()   { asm(\"pushf; pop %ax; bts $8,%ax; push %ax; popf; sysenter\"); }    $ gcc -o sysenter_step sysenter_step.c    $ ./sysenter_step   Segmentation fault (core dumped)  The program is expected to crash, and the #DB handler will issue a warning.  Kernel log:    WARNING: CPU: 27 PID: 7000 at arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160   ...   RIP: 0010:exc_debug_kernel+0xd2/0x160   ...   Call Trace:   \u003c#DB\u003e    ? show_regs+0x68/0x80    ? __warn+0x8c/0x140    ? exc_debug_kernel+0xd2/0x160    ? report_bug+0x175/0x1a0    ? handle_bug+0x44/0x90    ? exc_invalid_op+0x1c/0x70    ? asm_exc_invalid_op+0x1f/0x30    ? exc_debug_kernel+0xd2/0x160    exc_debug+0x43/0x50    asm_exc_debug+0x1e/0x40   RIP: 0010:clear_bhb_loop+0x0/0xb0   ...   \u003c/#DB\u003e   \u003cTASK\u003e    ? entry_SYSENTER_compat_after_hwframe+0x6e/0x8d   \u003c/TASK\u003e    [ bp: Massage commit message. ]","modified":"2026-09-15T09:03:10.203440395Z","published":"2024-08-07T16:15:46.810Z","upstream":["CVE-2024-42240"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-42240"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.106-1"}]}],"versions":["6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-42240.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.9.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-42240.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.9.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-42240.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}