Warn users about machines with non-working WP bit
Hi!
This might be good idea, as those machines are not safe for multiuser systems.
arch/i386/mm/init.c +1 -1
@@ -383,7 +383,7 @@local_flush_tlb ();if (!boot_cpu_data.wp_works_ok) { -printk ("No.\n" ); +printk ("No (that's security hole).\n" );#ifdef CONFIG_X86_WP_WORKS_OK panic ("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!" );#endif
Pavel
Signature · 2 lines
(about SSSCA) "I don't say this lightly. However, I really think that the U.S. no longer is classifiable as a democracy, but rather as a plutocracy." --hpa
Quoted 18 lines · Pavel Machek
Hi!
This might be good idea, as those machines are not safe for multiuser systems.
arch/i386/mm/init.c Mon Mar 11 21:49:14 2002 renamed from arch/i386/mm/init.c Sun Mar 10 20:06:31 2002 +1
-1@@ -383,7 +383,7 @@ local_flush_tlb(); if (!boot_cpu_data.wp_works_ok) { - printk("No.\n"); + printk("No (that's security hole).\n"); #ifdef CONFIG_X86_WP_WORKS_OK panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!"); #endif
Quoted 1 line
Pavel
The "bug" is really the lack of a feature present on 486+ cpus. A 386 will allow the kernel to write to a write-protected user page (but not a write-protected kernel page). In user mode, write protect works as it should. The kernel works around this by doing extra checks when writing to user pages (check the *_user() functions). It is not a security hole, because if the kernel wasn't compiled with the workaround, it refuses to boot on those cpus.
--
Brian Gerst
Hi!
Quoted 15 lines
Quoted 15 lines
This might be good idea, as those machines are not safe for multiuser systems.
arch/i386/mm/init.c Mon Mar 11 21:49:14 2002 renamed from arch/i386/mm/init.c Sun Mar 10 20:06:31 2002 +1
-1@@ -383,7 +383,7 @@ local_flush_tlb(); if (!boot_cpu_data.wp_works_ok) { - printk("No.\n"); + printk("No (that's security hole).\n"); #ifdef CONFIG_X86_WP_WORKS_OK panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!"); #endif
Quoted 7 lines
Quoted 1 line
Pavel
The "bug" is really the lack of a feature present on 486+ cpus. A 386 will allow the kernel to write to a write-protected user page (but not a write-protected kernel page). In user mode, write protect works as it should. The kernel works around this by doing extra checks when writing to user pages (check the
*_user()functions). It is not a security
It is, because those checks are racy when clone() is in use. Linus stated that few times.
Pavel
Signature · 2 lines
Casualities in World Trade Center: ~3k dead inside the building, cryptography in U.S.A. and free speech in Czech Republic.