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Diffstat (limited to 'arch/x86/kernel/kprobes/opt.c')
-rw-r--r--arch/x86/kernel/kprobes/opt.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 041f0b50bc27..08eb23074f92 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -272,6 +272,19 @@ static int insn_is_indirect_jump(struct insn *insn)
return ret;
}
+static bool is_padding_int3(unsigned long addr, unsigned long eaddr)
+{
+ unsigned char ops;
+
+ for (; addr < eaddr; addr++) {
+ if (get_kernel_nofault(ops, (void *)addr) < 0 ||
+ ops != INT3_INSN_OPCODE)
+ return false;
+ }
+
+ return true;
+}
+
/* Decode whole function to ensure any instructions don't jump into target */
static int can_optimize(unsigned long paddr)
{
@@ -310,9 +323,14 @@ static int can_optimize(unsigned long paddr)
return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
- /* Another subsystem puts a breakpoint */
+ /*
+ * In the case of detecting unknown breakpoint, this could be
+ * a padding INT3 between functions. Let's check that all the
+ * rest of the bytes are also INT3.
+ */
if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
- return 0;
+ return is_padding_int3(addr, paddr - offset + size) ? 1 : 0;
+
/* Recover address */
insn.kaddr = (void *)addr;
insn.next_byte = (void *)(addr + insn.length);