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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, Brian Gerst <brgerst@gmail.com>,
	Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 05/11] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS
Date: Thu, 14 Jul 2016 13:22:53 -0700	[thread overview]
Message-ID: <e626d47a55d7b04dcb1b4d33faa95e8505b217c8.1468527351.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1468527351.git.luto@kernel.org>
In-Reply-To: <cover.1468527351.git.luto@kernel.org>

If we overflow the stack into a guard page, we'll recursively fault
when trying to dump the contents of the guard page.  Use
probe_kernel_address so we can recover if this happens.

Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/kernel/dumpstack_64.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index d558a8a49016..2552a1eadfed 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -272,6 +272,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 
 	stack = sp;
 	for (i = 0; i < kstack_depth_to_print; i++) {
+		unsigned long word;
+
 		if (stack >= irq_stack && stack <= irq_stack_end) {
 			if (stack == irq_stack_end) {
 				stack = (unsigned long *) (irq_stack_end[-1]);
@@ -281,12 +283,18 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		if (kstack_end(stack))
 			break;
 		}
+
+		if (probe_kernel_address(stack, word))
+			break;
+
 		if ((i % STACKSLOTS_PER_LINE) == 0) {
 			if (i != 0)
 				pr_cont("\n");
-			printk("%s %016lx", log_lvl, *stack++);
+			printk("%s %016lx", log_lvl, word);
 		} else
-			pr_cont(" %016lx", *stack++);
+			pr_cont(" %016lx", word);
+
+		stack++;
 		touch_nmi_watchdog();
 	}
 	preempt_enable();
-- 
2.7.4

  parent reply	other threads:[~2016-07-14 20:23 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-14 20:22 [PATCH 00/11] x86: misc prep patches for virtually mapped stacks Andy Lutomirski
2016-07-14 20:22 ` [PATCH 01/11] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski
2016-07-14 20:22   ` Andy Lutomirski
2016-07-15 11:59   ` [tip:x86/mm] " tip-bot for Ingo Molnar
2016-07-14 20:22 ` [PATCH 02/11] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski
2016-07-15 11:59   ` [tip:x86/mm] x86/mm/cpa: In populate_pgd(), don't set the PGD " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 03/11] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() Andy Lutomirski
2016-07-15 12:00   ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 04/11] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski
2016-07-15 12:00   ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` Andy Lutomirski [this message]
2016-07-15 12:01   ` [tip:x86/mm] x86/dumpstack/64: Handle faults when printing the "Stack: " part of an OOPS tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 06/11] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm Andy Lutomirski
2016-07-15 12:01   ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 07/11] x86/dumpstack: When OOPSing, rewind the stack before do_exit() Andy Lutomirski
2016-07-15 12:02   ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 08/11] x86: Move uaccess_err and sig_on_uaccess_err to thread_struct Andy Lutomirski
2016-07-15  8:14   ` Ingo Molnar
2016-07-15 12:02   ` [tip:x86/mm] x86/uaccess: Move thread_info::uaccess_err and thread_info::sig_on_uaccess_err " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 09/11] x86: Move addr_limit " Andy Lutomirski
2016-07-15 12:03   ` [tip:x86/mm] x86/uaccess: Move thread_info::addr_limit " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 10/11] x86/smp: Remove stack_smp_processor_id() Andy Lutomirski
2016-07-15 12:04   ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2016-07-14 20:22 ` [PATCH 11/11] x86/smp: Remove unnecessary initialization of thread_info::cpu Andy Lutomirski
2016-07-15 12:04   ` [tip:x86/mm] " tip-bot for Andy Lutomirski

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