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5b10c8e436
Fix an oops in the stacktrace code, caused by improper range checking. We subtract 12 off 'fp' before testing to see if it's below the low bound. However, if 'fp' were zero before, it becomes a very large positive number, causing this test to succeed where it should fail. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
70 lines
1.4 KiB
C
70 lines
1.4 KiB
C
#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include "stacktrace.h"
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int walk_stackframe(unsigned long fp, unsigned long low, unsigned long high,
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int (*fn)(struct stackframe *, void *), void *data)
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{
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struct stackframe *frame;
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do {
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/*
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* Check current frame pointer is within bounds
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*/
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if (fp < (low + 12) || fp + 4 >= high)
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break;
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frame = (struct stackframe *)(fp - 12);
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if (fn(frame, data))
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break;
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/*
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* Update the low bound - the next frame must always
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* be at a higher address than the current frame.
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*/
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low = fp + 4;
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fp = frame->fp;
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} while (fp);
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return 0;
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}
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EXPORT_SYMBOL(walk_stackframe);
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#ifdef CONFIG_STACKTRACE
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struct stack_trace_data {
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struct stack_trace *trace;
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unsigned int skip;
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};
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static int save_trace(struct stackframe *frame, void *d)
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{
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struct stack_trace_data *data = d;
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struct stack_trace *trace = data->trace;
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if (data->skip) {
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data->skip--;
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return 0;
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}
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trace->entries[trace->nr_entries++] = frame->lr;
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return trace->nr_entries >= trace->max_entries;
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}
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void save_stack_trace(struct stack_trace *trace)
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{
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struct stack_trace_data data;
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unsigned long fp, base;
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data.trace = trace;
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data.skip = trace->skip;
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base = (unsigned long)task_stack_page(current);
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asm("mov %0, fp" : "=r" (fp));
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walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data);
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}
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#endif
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