git: bd8edba0792b - main - amd64 ia32_syscall(): only allow for ILP32 processes

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=bd8edba0792b71be3f8ed5dea9c22287e95c986a

commit bd8edba0792b71be3f8ed5dea9c22287e95c986a
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-04-25 09:49:08 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-04-27 03:23:19 +0000

    amd64 ia32_syscall(): only allow for ILP32 processes
    
    64bit processes can issue INT $0x80 instruction, and get the syscall
    dispatched through ia32_syscall().  This works because syscall argument
    fetch and result return are selected from the process sysent.
    
    But, ia32_syscall() does not verify some conditions and does not perform
    some actions which are considered unnecessary because the caller is
    supposed to only access lower 4G.  The INT syscall path breaks this
    assumption.
    
    We never supported such hack, so disable it.  Send the offending thread
    SIGBUS as if #GP was issued by hardware due to IDT vector 0x80 having
    not numerically high enough DPL value.
    
    Reviewed by:    markj
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
    Differential revision:  https://reviews.freebsd.org/D56630
---
 sys/amd64/ia32/ia32_syscall.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sys/amd64/ia32/ia32_syscall.c b/sys/amd64/ia32/ia32_syscall.c
index 85e3d8f8e920..edafb753faa0 100644
--- a/sys/amd64/ia32/ia32_syscall.c
+++ b/sys/amd64/ia32/ia32_syscall.c
@@ -218,6 +218,15 @@ ia32_syscall(struct trapframe *frame)
 	orig_tf_rflags = frame->tf_rflags;
 	td = curthread;
 	td->td_frame = frame;
+	if (__predict_false(SV_PROC_FLAG(td->td_proc, SV_ILP32) == 0)) {
+		ksiginfo_init_trap(&ksi);
+		ksi.ksi_signo = SIGBUS;
+		ksi.ksi_code = BUS_OBJERR;
+		ksi.ksi_addr = (void *)frame->tf_rip;
+		trapsignal(td, &ksi);
+		userret(td, td->td_frame);
+		return;
+	}
 
 	syscallenter(td);