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authorAlexander Potapenko <glider@google.com>2022-09-15 18:04:07 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-10-04 00:03:24 +0300
commitb11671b37f8f4761ff5a3d344553d65238309954 (patch)
treeb3e958a3849fadca7a95b5c1fb060c782888f81b
parent93324e6842148cfdb44d1437fb586b957ace1f8c (diff)
downloadlinux-b11671b37f8f4761ff5a3d344553d65238309954.tar.xz
x86: kmsan: skip shadow checks in __switch_to()
When instrumenting functions, KMSAN obtains the per-task state (mostly pointers to metadata for function arguments and return values) once per function at its beginning, using the `current` pointer. Every time the instrumented function calls another function, this state (`struct kmsan_context_state`) is updated with shadow/origin data of the passed and returned values. When `current` changes in the low-level arch code, instrumented code can not notice that, and will still refer to the old state, possibly corrupting it or using stale data. This may result in false positive reports. To deal with that, we need to apply __no_kmsan_checks to the functions performing context switching - this will result in skipping all KMSAN shadow checks and marking newly created values as initialized, preventing all false positive reports in those functions. False negatives are still possible, but we expect them to be rare and impersistent. Link: https://lkml.kernel.org/r/20220915150417.722975-34-glider@google.com Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--arch/x86/kernel/process_64.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 1962008fe743..6b3418bff326 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -553,6 +553,7 @@ void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp, bool x32)
* Kprobes not supported here. Set the probe on schedule instead.
* Function graph tracer not supported too.
*/
+__no_kmsan_checks
__visible __notrace_funcgraph struct task_struct *
__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
{