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arm64: don't call break hooks for BRK exceptions from EL0

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Our break hooks are used to handle brk exceptions from kgdb (and potentially
kprobes if that code ever resurfaces), so don't bother calling them if
the BRK exception comes from userspace.

This prevents userspace from trapping to a kdb shell on systems where
kgdb is enabled and active.

Cc: <stable@vger.kernel.org>
Reported-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2014-07-31 11:36:08 +01:00
parent 3666f88010
commit c878e0cff5
1 changed files with 11 additions and 11 deletions
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22
arch/arm64/kernel/debug-monitors.c
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@@ -315,20 +315,20 @@ static int brk_handler(unsigned long addr, unsigned int esr,
{
siginfo_t info;
if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED)
return 0;
if (user_mode(regs)) {
info = (siginfo_t) {
.si_signo = SIGTRAP,
.si_errno = 0,
.si_code = TRAP_BRKPT,
.si_addr = (void __user *)instruction_pointer(regs),
};
if (!user_mode(regs))
force_sig_info(SIGTRAP, &info, current);
} else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) {
pr_warning("Unexpected kernel BRK exception at EL1\n");
return -EFAULT;
}
info = (siginfo_t) {
.si_signo = SIGTRAP,
.si_errno = 0,
.si_code = TRAP_BRKPT,
.si_addr = (void __user *)instruction_pointer(regs),
};
force_sig_info(SIGTRAP, &info, current);
return 0;
}