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arm64: traps: Don't print stack or raw PC/LR values in backtraces

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Printing raw pointer values in backtraces has potential security
implications and are of questionable value anyway.

This patch follows x86's lead and removes the "Exception stack:" dump
from kernel backtraces, as well as converting PC/LR values to symbols
such as "sysrq_handle_crash+0x20/0x30".

Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2017-10-19 13:19:20 +01:00
parent 42dbf54e88
commit a25ffd3a63
2 changed files with 6 additions and 67 deletions
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8
arch/arm64/kernel/process.c
View file

@ -186,11 +186,9 @@ void __show_regs(struct pt_regs *regs)
} }
show_regs_print_info(KERN_DEFAULT); show_regs_print_info(KERN_DEFAULT);
print_symbol("PC is at %s\n", instruction_pointer(regs)); print_symbol("pc : %s\n", regs->pc);
print_symbol("LR is at %s\n", lr); print_symbol("lr : %s\n", lr);
printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n", printk("sp : %016llx pstate : %08llx\n", sp, regs->pstate);
regs->pc, lr, regs->pstate);
printk("sp : %016llx\n", sp);
i = top_reg; i = top_reg;

65
arch/arm64/kernel/traps.c
View file

@ -58,55 +58,9 @@ static const char *handler[]= {
int show_unhandled_signals = 1; int show_unhandled_signals = 1;
/*
* Dump out the contents of some kernel memory nicely...
*/
static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top)
{
unsigned long first;
mm_segment_t fs;
int i;
/*
* We need to switch to kernel mode so that we can use __get_user
* to safely read from kernel space.
*/
fs = get_fs();
set_fs(KERNEL_DS);
printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
for (first = bottom & ~31; first < top; first += 32) {
unsigned long p;
char str[sizeof(" 12345678") * 8 + 1];
memset(str, ' ', sizeof(str));
str[sizeof(str) - 1] = '\0';
for (p = first, i = 0; i < (32 / 8)
&& p < top; i++, p += 8) {
if (p >= bottom && p < top) {
unsigned long val;
if (__get_user(val, (unsigned long *)p) == 0)
sprintf(str + i * 17, " %016lx", val);
else
sprintf(str + i * 17, " ????????????????");
}
}
printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
}
set_fs(fs);
}
static void dump_backtrace_entry(unsigned long where) static void dump_backtrace_entry(unsigned long where)
{ {
/* printk(" %pS\n", (void *)where);
* Note that 'where' can have a physical address, but it's not handled.
*/
print_ip_sym(where);
} }
static void __dump_instr(const char *lvl, struct pt_regs *regs) static void __dump_instr(const char *lvl, struct pt_regs *regs)
@ -171,10 +125,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
skip = !!regs; skip = !!regs;
printk("Call trace:\n"); printk("Call trace:\n");
while (1) { do {
unsigned long stack;
int ret;
/* skip until specified stack frame */ /* skip until specified stack frame */
if (!skip) { if (!skip) {
dump_backtrace_entry(frame.pc); dump_backtrace_entry(frame.pc);
@ -189,17 +140,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
*/ */
dump_backtrace_entry(regs->pc); dump_backtrace_entry(regs->pc);
} }
ret = unwind_frame(tsk, &frame); } while (!unwind_frame(tsk, &frame));
if (ret < 0)
break;
if (in_entry_text(frame.pc)) {
stack = frame.fp - offsetof(struct pt_regs, stackframe);
if (on_accessible_stack(tsk, stack))
dump_mem("", "Exception stack", stack,
stack + sizeof(struct pt_regs));
}
}
put_task_stack(tsk); put_task_stack(tsk);
} }