linux-kernel - [PATCH 1/3] lguest: fix sense if IF flag on interrupt injection

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 20 Jul 2007 22:11:13 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
	virtualization <virtualization@...ts.linux-foundation.org>
Subject: [PATCH 1/3] lguest: fix sense if IF flag on interrupt injection

The sense of the IF bit is backwards in the host interrupt handling.

This means we always save "IF=1" on the stack when injecting an
interrupt.  It turns out this is almost always correct (unless the
guest is taking a page fault in an interrupt due to an unpopulated
vmalloc mapping), so went unnoticed.

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 drivers/lguest/interrupts_and_traps.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff -r 209f5cd5cda5 drivers/lguest/interrupts_and_traps.c
--- a/drivers/lguest/interrupts_and_traps.c	Fri Jul 20 14:53:40 2007 +1000
+++ b/drivers/lguest/interrupts_and_traps.c	Fri Jul 20 21:34:06 2007 +1000
@@ -38,12 +38,12 @@ static void set_guest_interrupt(struct l
 		ss = lg->regs->ss;
 	}
 
-	/* We use IF bit in eflags to indicate whether irqs were disabled
-	   (it's always 0, since irqs are enabled when guest is running). */
+	/* We use IF bit in eflags to indicate whether irqs were enabled
+	   (it's always 1, since irqs are enabled when guest is running). */
 	eflags = lg->regs->eflags;
-	if (get_user(irq_enable, &lg->lguest_data->irq_enabled))
-		irq_enable = 0;
-	eflags |= (irq_enable & X86_EFLAGS_IF);
+	if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0
+	    && !(irq_enable & X86_EFLAGS_IF))
+		eflags &= ~X86_EFLAGS_IF;
 
 	push_guest_stack(lg, &gstack, eflags);
 	push_guest_stack(lg, &gstack, lg->regs->cs);


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/