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authorWill Deacon <will.deacon@arm.com>2014-07-31 11:36:08 +0100
committerWill Deacon <will.deacon@arm.com>2014-07-31 11:36:08 +0100
commitc878e0cff5c5e56b216951cbe75f7a3dd500a736 (patch)
tree234fca64e4707b18b7c1bfe354348e9a096badbf /arch/arm64
parent3666f88010d71e752ad677ec64edf148366afb7a (diff)
arm64: don't call break hooks for BRK exceptions from EL0
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>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/kernel/debug-monitors.c22
1 files changed, 11 insertions, 11 deletions
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index a7fb874b595e..fe5b94078d82 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -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;
}