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Message-Id: <539f9b6f7ef8c23d416a3d4841f1a25135cc37e4.1466036668.git.luto@kernel.org> Date: Wed, 15 Jun 2016 17:28:33 -0700 From: Andy Lutomirski <luto@...nel.org> To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, x86@...nel.org, Borislav Petkov <bp@...en8.de> Cc: Nadav Amit <nadav.amit@...il.com>, Kees Cook <keescook@...omium.org>, Brian Gerst <brgerst@...il.com>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Josh Poimboeuf <jpoimboe@...hat.com>, Andy Lutomirski <luto@...nel.org> Subject: [PATCH 11/13] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS 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@...nel.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 603356a5597a..5e298638c790 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -276,6 +276,8 @@ 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]); @@ -285,12 +287,18 @@ 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
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