Merge tag 'perf-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

torvalds · torvalds · commit 4f61f842d199 · 2022-08-21T15:01:51.000-07:00
Pull x86 kprobes fix from Ingo Molnar:
 "Fix a kprobes bug in JNG/JNLE emulation when a kprobe is installed at
  such instructions, possibly resulting in incorrect execution (the
  wrong branch taken)"

* tag 'perf-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kprobes: Fix JNG/JNLE emulation
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
@@ -505,7 +505,7 @@ static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs)
 		match = ((regs->flags & X86_EFLAGS_SF) >> X86_EFLAGS_SF_BIT) ^
 			((regs->flags & X86_EFLAGS_OF) >> X86_EFLAGS_OF_BIT);
 		if (p->ainsn.jcc.type >= 0xe)
-			match = match && (regs->flags & X86_EFLAGS_ZF);
+			match = match || (regs->flags & X86_EFLAGS_ZF);
 	}
 	__kprobe_emulate_jmp(p, regs, (match && !invert) || (!match && invert));
 }

Original file line number	Diff line number	Diff line change
`@@ -505,7 +505,7 @@ static void kprobe_emulate_jcc(struct kprobe p, struct pt_regs regs)`
`505`	`505`	`match = ((regs->flags & X86_EFLAGS_SF) >> X86_EFLAGS_SF_BIT) ^`
`506`	`506`	`((regs->flags & X86_EFLAGS_OF) >> X86_EFLAGS_OF_BIT);`
`507`	`507`	`if (p->ainsn.jcc.type >= 0xe)`
`508`		`- match = match && (regs->flags & X86_EFLAGS_ZF);`
	`508`	`+ match = match \|\| (regs->flags & X86_EFLAGS_ZF);`
`509`	`509`	`}`
`510`	`510`	`__kprobe_emulate_jmp(p, regs, (match && !invert) \|\| (!match && invert));`
`511`	`511`	`}`