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x86/dumpstack/64: Handle faults when printing the "Stack: " part of an OOPS

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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.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/e626d47a55d7b04dcb1b4d33faa95e8505b217c8.1468527351.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2016-07-14 13:22:53 -07:00 committed by Ingo Molnar
parent 9a2e9da3e0
commit 98f30b1207
1 changed files with 10 additions and 2 deletions
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12
arch/x86/kernel/dumpstack_64.c
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@ -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();