diff --git a/kernel.spec b/kernel.spec index d3d2022..dfd0249 100644 --- a/kernel.spec +++ b/kernel.spec @@ -786,6 +786,9 @@ Patch2150: 3.7.3-stable-queue.patch #rhbz 886946 Patch21234: iwlegacy-fix-IBSS-cleanup.patch +#rhbz 896051 896038 CVE-2013-0190 +Patch21250: xen-fix-stack-corruption-in-xen_failsafe_callback.patch + # END OF PATCH DEFINITIONS %endif @@ -1511,6 +1514,9 @@ ApplyPatch 3.7.3-stable-queue.patch #rhbz 886948 ApplyPatch iwlegacy-fix-IBSS-cleanup.patch +#rhbz 896051 896038 CVE-2013-0190 +ApplyPatch xen-fix-stack-corruption-in-xen_failsafe_callback.patch + # END OF PATCH APPLICATIONS %endif @@ -2383,6 +2389,9 @@ fi # ||----w | # || || %changelog +* Wed Jan 16 2013 Justin M. Forbes 3.7.2-204 +- Fix for CVE-2013-0190 xen corruption with 32bit pvops (rhbz 896051 896038) + * Wed Jan 16 2013 Josh Boyer - Add patch from Stanislaw Gruszka to fix iwlegacy IBSS cleanup (rhbz 886946) diff --git a/xen-fix-stack-corruption-in-xen_failsafe_callback.patch b/xen-fix-stack-corruption-in-xen_failsafe_callback.patch new file mode 100644 index 0000000..9d83ea0 --- /dev/null +++ b/xen-fix-stack-corruption-in-xen_failsafe_callback.patch @@ -0,0 +1,62 @@ +From 38174c8c07ad638cd18285ba402b59076849dc21 Mon Sep 17 00:00:00 2001 +From: Andrew Cooper +Date: Thu, 10 Jan 2013 17:16:30 +0000 +Subject: [PATCH] xen: Fix stack corruption in xen_failsafe_callback for 32bit PVOPS guests. + +There has been an error on the xen_failsafe_callback path for failed +iret, which causes the stack pointer to be wrong when entering the +iret_exc error path. This can result in the kernel crashing. + +In the classic kernel case, the relevant code looked a little like: + + popl %eax # Error code from hypervisor + jz 5f + addl $16,%esp + jmp iret_exc # Hypervisor said iret fault +5: addl $16,%esp + # Hypervisor said segment selector fault + +Here, there are two identical addls on either option of a branch which +appears to have been optimised by hoisting it above the jz, and +converting it to an lea, which leaves the flags register unaffected. + +In the PVOPS case, the code looks like: + + popl_cfi %eax # Error from the hypervisor + lea 16(%esp),%esp # Add $16 before choosing fault path + CFI_ADJUST_CFA_OFFSET -16 + jz 5f + addl $16,%esp # Incorrectly adjust %esp again + jmp iret_exc + +It is possible unprivileged userspace applications to cause this +behaviour, for example by loading an LDT code selector, then changing +the code selector to be not-present. At this point, there is a race +condition where it is possible for the hypervisor to return back to +userspace from an interrupt, fault on its own iret, and inject a +failsafe_callback into the kernel. + +This bug has been present since the introduction of Xen PVOPS support +in commit 5ead97c84 (xen: Core Xen implementation), in 2.6.23. + +Signed-off-by: Frediano Ziglio +Signed-off-by: Andrew Cooper +--- + arch/x86/kernel/entry_32.S | 1 - + 1 files changed, 0 insertions(+), 1 deletions(-) + +diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S +index ff84d54..6ed91d9 100644 +--- a/arch/x86/kernel/entry_32.S ++++ b/arch/x86/kernel/entry_32.S +@@ -1065,7 +1065,6 @@ ENTRY(xen_failsafe_callback) + lea 16(%esp),%esp + CFI_ADJUST_CFA_OFFSET -16 + jz 5f +- addl $16,%esp + jmp iret_exc + 5: pushl_cfi $-1 /* orig_ax = -1 => not a system call */ + SAVE_ALL +-- +1.7.2.5 +