| Message ID | 7f322fe9-34ba-43be-bb50-539577d1c183@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] x86: disable non-instrumented version of copy_page when KMSAN is enabled | expand |
diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h index cc6b8e087192..f13bba3a9dab 100644 --- a/arch/x86/include/asm/page_64.h +++ b/arch/x86/include/asm/page_64.h @@ -58,7 +58,16 @@ static inline void clear_page(void *page) : "cc", "memory", "rax", "rcx"); } +#ifdef CONFIG_KMSAN +/* Use of non-instrumented assembly version confuses KMSAN. */ +void *memcpy(void *to, const void *from, __kernel_size_t len); +static inline void copy_page(void *to, void *from) +{ + memcpy(to, from, PAGE_SIZE); +} +#else void copy_page(void *to, void *from); +#endif #ifdef CONFIG_X86_5LEVEL /*
I found that commit afb2d666d025 ("zsmalloc: use copy_page for full page copy") caused a false-positive KMSAN warning. [ 50.030627][ T2974] BUG: KMSAN: use-after-free in obj_malloc+0x6cc/0x7b0 [ 50.165956][ T2974] Uninit was stored to memory at: [ 50.170819][ T2974] obj_malloc+0x70a/0x7b0 [ 50.328931][ T2974] Uninit was created at: [ 50.341845][ T2974] free_unref_page_prepare+0x130/0xfc0 We need to use instrumented version when KMSAN is enabled. Let arch/x86/include/asm/page_64.h implement copy_page() using memcpy() like arch/x86/include/asm/page_32.h does. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- arch/x86/include/asm/page_64.h | 9 +++++++++ 1 file changed, 9 insertions(+) Changes in v2: Update explanation, for I misinterpreted source/destination direction.