From: "tip-bot2 for Joerg Roedel" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>, Joerg Roedel <jroedel@suse.de>,
Borislav Petkov <bp@suse.de>,
stable@vger.kernel.org, #@tip-bot2.tec.linutronix.de,
5.10+@tip-bot2.tec.linutronix.de, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: [tip: x86/urgent] x86/sev-es: Check regs->sp is trusted before adjusting #VC IST stack
Date: Tue, 09 Mar 2021 16:08:12 -0000 [thread overview]
Message-ID: <161530609222.398.7645217212660727699.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210303141716.29223-3-joro@8bytes.org>
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 545ac14c16b5dbd909d5a90ddf5b5a629a40fa94
Gitweb: https://git.kernel.org/tip/545ac14c16b5dbd909d5a90ddf5b5a629a40fa94
Author: Joerg Roedel <jroedel@suse.de>
AuthorDate: Wed, 03 Mar 2021 15:17:13 +01:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 09 Mar 2021 12:26:26 +01:00
x86/sev-es: Check regs->sp is trusted before adjusting #VC IST stack
The code in the NMI handler to adjust the #VC handler IST stack is
needed in case an NMI hits when the #VC handler is still using its IST
stack.
But the check for this condition also needs to look if the regs->sp
value is trusted, meaning it was not set by user-space. Extend the check
to not use regs->sp when the NMI interrupted user-space code or the
SYSCALL gap.
Fixes: 315562c9af3d5 ("x86/sev-es: Adjust #VC IST Stack on entering NMI handler")
Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org # 5.10+
Link: https://lkml.kernel.org/r/20210303141716.29223-3-joro@8bytes.org
---
arch/x86/kernel/sev-es.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 84c1821..301f20f 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -121,8 +121,18 @@ static void __init setup_vc_stacks(int cpu)
cea_set_pte((void *)vaddr, pa, PAGE_KERNEL);
}
-static __always_inline bool on_vc_stack(unsigned long sp)
+static __always_inline bool on_vc_stack(struct pt_regs *regs)
{
+ unsigned long sp = regs->sp;
+
+ /* User-mode RSP is not trusted */
+ if (user_mode(regs))
+ return false;
+
+ /* SYSCALL gap still has user-mode RSP */
+ if (ip_within_syscall_gap(regs))
+ return false;
+
return ((sp >= __this_cpu_ist_bottom_va(VC)) && (sp < __this_cpu_ist_top_va(VC)));
}
@@ -144,7 +154,7 @@ void noinstr __sev_es_ist_enter(struct pt_regs *regs)
old_ist = __this_cpu_read(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC]);
/* Make room on the IST stack */
- if (on_vc_stack(regs->sp))
+ if (on_vc_stack(regs))
new_ist = ALIGN_DOWN(regs->sp, 8) - sizeof(old_ist);
else
new_ist = old_ist - sizeof(old_ist);
next prev parent reply other threads:[~2021-03-09 16:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 14:17 [PATCH 0/5 v2] x86/sev-es: SEV-ES Fixes for v5.12 Joerg Roedel
2021-03-03 14:17 ` [PATCH 1/5] x86/sev-es: Introduce ip_within_syscall_gap() helper Joerg Roedel
2021-03-09 16:08 ` [tip: x86/urgent] " tip-bot2 for Joerg Roedel
2021-03-03 14:17 ` [PATCH 2/5] x86/sev-es: Check if regs->sp is trusted before adjusting #VC IST stack Joerg Roedel
2021-03-09 16:08 ` tip-bot2 for Joerg Roedel [this message]
2021-03-03 14:17 ` [PATCH 3/5] x86/sev-es: Optimize __sev_es_ist_enter() for better readability Joerg Roedel
2021-03-19 13:17 ` [tip: x86/seves] " tip-bot2 for Joerg Roedel
2021-03-03 14:17 ` [PATCH 4/5] x86/sev-es: Correctly track IRQ states in runtime #VC handler Joerg Roedel
2021-03-09 16:08 ` [tip: x86/urgent] " tip-bot2 for Joerg Roedel
2021-03-03 14:17 ` [PATCH 5/5] x86/sev-es: Use __copy_from_user_inatomic() Joerg Roedel
2021-03-09 16:08 ` [tip: x86/urgent] " tip-bot2 for Joerg Roedel
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