x86/entry: Do not allow external 0x80 interrupts
authorThomas Gleixner <tglx@linutronix.de>
Mon, 4 Dec 2023 08:31:40 +0000 (11:31 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 13 Dec 2023 17:45:02 +0000 (18:45 +0100)
commit22ca647c8f880f21881e9b2d38070dc61196a39d
tree53ef1440162e75cae7634a5517272e1ce4d281b9
parent4591766ff6552339fbaa3d3c71814faef1988c2f
x86/entry: Do not allow external 0x80 interrupts

[ upstream commit 55617fb991df535f953589586468612351575704 ]

The INT 0x80 instruction is used for 32-bit x86 Linux syscalls. The
kernel expects to receive a software interrupt as a result of the INT
0x80 instruction. However, an external interrupt on the same vector
also triggers the same codepath.

An external interrupt on vector 0x80 will currently be interpreted as a
32-bit system call, and assuming that it was a user context.

Panic on external interrupts on the vector.

To distinguish software interrupts from external ones, the kernel checks
the APIC ISR bit relevant to the 0x80 vector. For software interrupts,
this bit will be 0.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@vger.kernel.org> # v6.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/entry/common.c