[PATCH v5 07/10] x86/kgdb: avoid redundant comparison of patched code
From: Nadav Amit <hidden>
Date: 2018-11-13 20:26:28
Also in:
linux-security-module, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
text_poke() already ensures that the written value is the correct one and fails if that is not the case. There is no need for an additional comparison. Remove it. Signed-off-by: Nadav Amit <redacted> --- arch/x86/kernel/kgdb.c | 10 ---------- 1 file changed, 10 deletions(-)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8091b2e381d4..d14e1be576fd 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c@@ -751,7 +751,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) { int err; - char opc[BREAK_INSTR_SIZE]; bpt->type = BP_BREAKPOINT; err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
@@ -772,11 +771,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) BREAK_INSTR_SIZE); if (err) return err; - err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); - if (err) - return err; - if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE)) - return -EINVAL; bpt->type = BP_POKE_BREAKPOINT; return err;
@@ -785,7 +779,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) { int err; - char opc[BREAK_INSTR_SIZE]; if (bpt->type != BP_POKE_BREAKPOINT) goto knl_write;
@@ -798,9 +791,6 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) err = text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE); if (err) - return err; - err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); - if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE)) goto knl_write; return err;
--
2.17.1