Messages in this thread Patch in this message | | | Date | Wed, 2 Nov 2022 12:06:11 +0100 | Subject | [PATCH 5/5] x86/traps: avoid KMSAN bugs originating from handle_bug() | From | Alexander Potapenko <> |
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There is a case in exc_invalid_op handler that is executed outside the irqentry_enter()/irqentry_exit() region when an UD2 instruction is used to encode a call to __warn().
In that case the `struct pt_regs` passed to the interrupt handler is never unpoisoned by KMSAN (this is normally done in irqentry_enter()), which leads to false positives inside handle_bug().
Use kmsan_unpoison_entry_regs() to explicitly unpoison those registers before using them.
Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org Signed-off-by: Alexander Potapenko <glider@google.com> --- arch/x86/kernel/traps.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 178015a820f08..d3fdec706f1d2 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -15,6 +15,7 @@ #include <linux/context_tracking.h> #include <linux/interrupt.h> #include <linux/kallsyms.h> +#include <linux/kmsan.h> #include <linux/spinlock.h> #include <linux/kprobes.h> #include <linux/uaccess.h> @@ -301,6 +302,12 @@ static noinstr bool handle_bug(struct pt_regs *regs) { bool handled = false; + /* + * Normally @regs are unpoisoned by irqentry_enter(), but handle_bug() + * is a rare case that uses @regs without passing them to + * irqentry_enter(). + */ + kmsan_unpoison_entry_regs(regs); if (!is_valid_bugaddr(regs->ip)) return handled; -- 2.38.1.273.g43a17bfeac-goog
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