From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
linux_dti@icloud.com, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, akpm@linux-foundation.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
will.deacon@arm.com, ard.biesheuvel@linaro.org,
kristen@linux.intel.com, deneen.t.dock@intel.com,
Nadav Amit <namit@vmware.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>
Subject: [PATCH v4 04/23] x86/mm: Save DRs when loading a temporary mm
Date: Mon, 22 Apr 2019 11:57:46 -0700 [thread overview]
Message-ID: <20190422185805.1169-5-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190422185805.1169-1-rick.p.edgecombe@intel.com>
From: Nadav Amit <namit@vmware.com>
Prevent user watchpoints from mistakenly firing while the temporary mm
is being used. As the addresses that of the temporary mm might overlap
those of the user-process, this is necessary to prevent wrong signals
or worse things from happening.
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
arch/x86/include/asm/mmu_context.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index d684b954f3c0..81861862038a 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -13,6 +13,7 @@
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>
+#include <asm/debugreg.h>
extern atomic64_t last_mm_ctx_id;
@@ -380,6 +381,21 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm)
lockdep_assert_irqs_disabled();
state.prev = this_cpu_read(cpu_tlbstate.loaded_mm);
switch_mm_irqs_off(NULL, mm, current);
+
+ /*
+ * If breakpoints are enabled, disable them while the temporary mm is
+ * used. Userspace might set up watchpoints on addresses that are used
+ * in the temporary mm, which would lead to wrong signals being sent or
+ * crashes.
+ *
+ * Note that breakpoints are not disabled selectively, which also causes
+ * kernel breakpoints (e.g., perf's) to be disabled. This might be
+ * undesirable, but still seems reasonable as the code that runs in the
+ * temporary mm should be short.
+ */
+ if (hw_breakpoint_active())
+ hw_breakpoint_disable();
+
return state;
}
@@ -387,6 +403,13 @@ static inline void unuse_temporary_mm(temp_mm_state_t prev)
{
lockdep_assert_irqs_disabled();
switch_mm_irqs_off(NULL, prev.prev, current);
+
+ /*
+ * Restore the breakpoints if they were disabled before the temporary mm
+ * was loaded.
+ */
+ if (hw_breakpoint_active())
+ hw_breakpoint_restore();
}
#endif /* _ASM_X86_MMU_CONTEXT_H */
--
2.17.1
next prev parent reply other threads:[~2019-04-22 19:00 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 18:57 [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 01/23] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 02/23] x86/jump_label: Use text_poke_early() during early init Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 03/23] x86/mm: Introduce temporary mm structs Rick Edgecombe
2019-04-25 16:26 ` Borislav Petkov
2019-04-25 17:37 ` Nadav Amit
2019-04-25 17:49 ` Andy Lutomirski
2019-04-22 18:57 ` Rick Edgecombe [this message]
2019-04-25 16:36 ` [PATCH v4 04/23] x86/mm: Save DRs when loading a temporary mm Borislav Petkov
2019-04-25 18:17 ` Peter Zijlstra
2019-04-22 18:57 ` [PATCH v4 05/23] fork: Provide a function for copying init_mm Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 06/23] x86/alternative: Initialize temporary mm for patching Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 07/23] x86/alternative: Use temporary mm for text poking Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 08/23] x86/kgdb: Avoid redundant comparison of patched code Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 09/23] x86/ftrace: Set trampoline pages as executable Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 10/23] x86/kprobes: Set instruction page " Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 11/23] x86/module: Avoid breaking W^X while loading modules Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 12/23] x86/jump-label: Remove support for custom poker Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 13/23] x86/alternative: Remove the return value of text_poke_*() Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 14/23] x86/mm/cpa: Add set_direct_map_ functions Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 15/23] mm: Make hibernate handle unmapped pages Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 16/23] vmalloc: Add flag for free of special permsissions Rick Edgecombe
2019-04-25 20:38 ` Peter Zijlstra
2019-04-25 21:22 ` Edgecombe, Rick P
2019-04-22 18:57 ` [PATCH v4 17/23] modules: Use vmalloc special flag Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 18/23] bpf: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 19/23] x86/ftrace: " Rick Edgecombe
2019-04-25 18:28 ` Steven Rostedt
2019-04-25 19:19 ` Edgecombe, Rick P
2019-04-22 18:58 ` [PATCH v4 20/23] x86/kprobes: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 21/23] x86/alternative: Comment about module removal races Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 22/23] tlb: provide default nmi_uaccess_okay() Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 23/23] bpf: Fail bpf_probe_write_user() while mm is switched Rick Edgecombe
2019-04-25 20:48 ` [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Peter Zijlstra
2019-04-25 20:49 ` Peter Zijlstra
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