ab285f2b52
When we fetch the hot regs and rewind to the nth caller, it
might happen that we dereference a frame pointer outside the
kernel stack boundaries, like in this example:
perf_trace_sched_switch+0xd5/0x120
schedule+0x6b5/0x860
retint_careful+0xd/0x21
Since we directly dereference a userspace frame pointer here while
rewinding behind retint_careful, this may end up in a crash.
Fix this by simply using probe_kernel_address() when we rewind the
frame pointer.
This issue will have a much more proper fix in the next version of the
perf_arch_fetch_caller_regs() API that will only need to rewind to the
first caller.
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: David Miller <davem@davemloft.net>
Cc: Archs <linux-arch@vger.kernel.org>
56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
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*/
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#ifndef DUMPSTACK_H
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#define DUMPSTACK_H
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#ifdef CONFIG_X86_32
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#define STACKSLOTS_PER_LINE 8
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#define get_bp(bp) asm("movl %%ebp, %0" : "=r" (bp) :)
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#else
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#define STACKSLOTS_PER_LINE 4
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#define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :)
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#endif
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#include <linux/uaccess.h>
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extern void
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show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
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unsigned long *stack, unsigned long bp, char *log_lvl);
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extern void
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show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
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unsigned long *sp, unsigned long bp, char *log_lvl);
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extern unsigned int code_bytes;
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/* The form of the top of the frame on the stack */
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struct stack_frame {
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struct stack_frame *next_frame;
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unsigned long return_address;
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};
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struct stack_frame_ia32 {
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u32 next_frame;
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u32 return_address;
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};
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static inline unsigned long rewind_frame_pointer(int n)
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{
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struct stack_frame *frame;
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get_bp(frame);
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#ifdef CONFIG_FRAME_POINTER
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while (n--) {
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if (probe_kernel_address(&frame->next_frame, frame))
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break;
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}
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#endif
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return (unsigned long)frame;
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}
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#endif /* DUMPSTACK_H */
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