entry: kmsan: introduce kmsan_unpoison_entry_regs()

struct pt_regs passed into IRQ entry code is set up by uninstrumented asm
functions, therefore KMSAN may not notice the registers are initialized.

kmsan_unpoison_entry_regs() unpoisons the contents of struct pt_regs,
preventing potential false positives.  Unlike kmsan_unpoison_memory(), it
can be called under kmsan_in_runtime(), which is often the case in IRQ
entry code.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Potapenko <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Ilya Leoshkevich <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 063068a9ea9b..846add8394c4 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -5,6 +5,7 @@
 #include <linux/resume_user_mode.h>
 #include <linux/highmem.h>
 #include <linux/jump_label.h>
+#include <linux/kmsan.h>
 #include <linux/livepatch.h>
 #include <linux/audit.h>
 #include <linux/tick.h>
@@ -24,6 +25,7 @@ static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
 	user_exit_irqoff();
 
 	instrumentation_begin();
+	kmsan_unpoison_entry_regs(regs);
 	trace_hardirqs_off_finish();
 	instrumentation_end();
 }
@@ -352,6 +354,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 		lockdep_hardirqs_off(CALLER_ADDR0);
 		ct_irq_enter();
 		instrumentation_begin();
+		kmsan_unpoison_entry_regs(regs);
 		trace_hardirqs_off_finish();
 		instrumentation_end();
 
@@ -367,6 +370,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 	 */
 	lockdep_hardirqs_off(CALLER_ADDR0);
 	instrumentation_begin();
+	kmsan_unpoison_entry_regs(regs);
 	rcu_irq_enter_check_tick();
 	trace_hardirqs_off_finish();
 	instrumentation_end();
@@ -452,6 +456,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
 	ct_nmi_enter();
 
 	instrumentation_begin();
+	kmsan_unpoison_entry_regs(regs);
 	trace_hardirqs_off_finish();
 	ftrace_nmi_enter();
 	instrumentation_end();