Because __asan_{load,store}{N,1,2,4,8,16}_noabort() get called from
UACCESS context, and kasan_report() is most definitely _NOT_ safe to
be called from there, move it into an exception much like BUG/WARN.

*compile tested only*

Cc: Andrey Ryabinin <aryabi...@virtuozzo.com>
Cc: Dmitry Vyukov <dvyu...@google.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
 arch/x86/include/asm/bug.h   |   28 ++++++++++++++--------------
 arch/x86/include/asm/kasan.h |   15 +++++++++++++++
 include/asm-generic/bug.h    |    1 +
 include/linux/kasan.h        |   12 +++++++++---
 lib/bug.c                    |    9 ++++++++-
 mm/kasan/generic.c           |    4 ++--
 mm/kasan/kasan.h             |    2 +-
 mm/kasan/report.c            |    2 +-
 8 files changed, 51 insertions(+), 22 deletions(-)

--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -30,33 +30,33 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
-#define _BUG_FLAGS(ins, flags)                                         \
+#define _BUG_FLAGS(ins, flags, ...)                                    \
 do {                                                                   \
        asm volatile("1:\t" ins "\n"                                    \
                     ".pushsection __bug_table,\"aw\"\n"                \
-                    "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
-                    "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"       \
-                    "\t.word %c1"        "\t# bug_entry::line\n"       \
-                    "\t.word %c2"        "\t# bug_entry::flags\n"      \
-                    "\t.org 2b+%c3\n"                                  \
+                    "2:\t" __BUG_REL(1b)      "\t# bug_entry::bug_addr\n" \
+                    "\t"  __BUG_REL(%c[file]) "\t# bug_entry::file\n"  \
+                    "\t.word %c[line]"        "\t# bug_entry::line\n"  \
+                    "\t.word %c[flag]"        "\t# bug_entry::flags\n" \
+                    "\t.org 2b+%c[size]\n"                             \
                     ".popsection"                                      \
-                    : : "i" (__FILE__), "i" (__LINE__),                \
-                        "i" (flags),                                   \
-                        "i" (sizeof(struct bug_entry)));               \
+                    : : [file] "i" (__FILE__), [line] "i" (__LINE__),  \
+                        [flag] "i" (flags),                            \
+                        [size] "i" (sizeof(struct bug_entry)), ##__VA_ARGS__); 
\
 } while (0)
 
 #else /* !CONFIG_DEBUG_BUGVERBOSE */
 
-#define _BUG_FLAGS(ins, flags)                                         \
+#define _BUG_FLAGS(ins, flags, ...)                                    \
 do {                                                                   \
        asm volatile("1:\t" ins "\n"                                    \
                     ".pushsection __bug_table,\"aw\"\n"                \
                     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
-                    "\t.word %c0"        "\t# bug_entry::flags\n"      \
-                    "\t.org 2b+%c1\n"                                  \
+                    "\t.word %c[flag]"   "\t# bug_entry::flags\n"      \
+                    "\t.org 2b+%c[size]\n"                             \
                     ".popsection"                                      \
-                    : : "i" (flags),                                   \
-                        "i" (sizeof(struct bug_entry)));               \
+                    : : [flag] "i" (flags),                            \
+                        [size] "i" (sizeof(struct bug_entry)), ##__VA_ARGS__); 
\
 } while (0)
 
 #endif /* CONFIG_DEBUG_BUGVERBOSE */
--- a/arch/x86/include/asm/kasan.h
+++ b/arch/x86/include/asm/kasan.h
@@ -2,6 +2,8 @@
 #ifndef _ASM_X86_KASAN_H
 #define _ASM_X86_KASAN_H
 
+#include <asm/bug.h>
+
 #include <linux/const.h>
 #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
 #define KASAN_SHADOW_SCALE_SHIFT 3
@@ -26,8 +28,21 @@
 #ifndef __ASSEMBLY__
 
 #ifdef CONFIG_KASAN
+
 void __init kasan_early_init(void);
 void __init kasan_init(void);
+
+static __always_inline void
+kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip)
+{
+       unsigned long rdi = addr, rsi = size, rdx = is_write, rcx = ip;
+
+       _BUG_FLAGS(ASM_UD2, BUGFLAG_KASAN,
+                  "D" (rdi), "S" (rsi), "d" (rdx), "c" (rcx));
+       annotate_reachable();
+}
+#define kasan_report kasan_report
+
 #else
 static inline void kasan_early_init(void) { }
 static inline void kasan_init(void) { }
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -10,6 +10,7 @@
 #define BUGFLAG_WARNING                (1 << 0)
 #define BUGFLAG_ONCE           (1 << 1)
 #define BUGFLAG_DONE           (1 << 2)
+#define BUGFLAG_KASAN          (1 << 3)
 #define BUGFLAG_TAINT(taint)   ((taint) << 8)
 #define BUG_GET_TAINT(bug)     ((bug)->flags >> 8)
 #endif
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -83,6 +83,9 @@ size_t kasan_metadata_size(struct kmem_c
 bool kasan_save_enable_multi_shot(void);
 void kasan_restore_multi_shot(bool enabled);
 
+void __kasan_report(unsigned long addr, size_t size,
+               bool is_write, unsigned long ip);
+
 #else /* CONFIG_KASAN */
 
 static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
@@ -153,8 +156,14 @@ static inline void kasan_remove_zero_sha
 static inline void kasan_unpoison_slab(const void *ptr) { }
 static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; 
}
 
+static inline void __kasan_report(unsigned long addr, size_t size, bool 
is_write, unsigned long ip) { }
+
 #endif /* CONFIG_KASAN */
 
+#ifndef kasan_report
+#define kasan_report(addr, size, is_write, ip) __kasan_report(addr, size, 
is_write, ip)
+#endif
+
 #ifdef CONFIG_KASAN_GENERIC
 
 #define KASAN_SHADOW_INIT 0
@@ -177,9 +186,6 @@ void kasan_init_tags(void);
 
 void *kasan_reset_tag(const void *addr);
 
-void kasan_report(unsigned long addr, size_t size,
-               bool is_write, unsigned long ip);
-
 #else /* CONFIG_KASAN_SW_TAGS */
 
 static inline void kasan_init_tags(void) { }
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -47,6 +47,7 @@
 #include <linux/bug.h>
 #include <linux/sched.h>
 #include <linux/rculist.h>
+#include <linux/kasan.h>
 
 extern struct bug_entry __start___bug_table[], __stop___bug_table[];
 
@@ -144,7 +145,7 @@ enum bug_trap_type report_bug(unsigned l
 {
        struct bug_entry *bug;
        const char *file;
-       unsigned line, warning, once, done;
+       unsigned line, warning, once, done, kasan;
 
        if (!is_valid_bugaddr(bugaddr))
                return BUG_TRAP_TYPE_NONE;
@@ -167,6 +168,7 @@ enum bug_trap_type report_bug(unsigned l
                line = bug->line;
 #endif
                warning = (bug->flags & BUGFLAG_WARNING) != 0;
+               kasan = (bug->flags & BUGFLAG_KASAN) != 0;
                once = (bug->flags & BUGFLAG_ONCE) != 0;
                done = (bug->flags & BUGFLAG_DONE) != 0;
 
@@ -188,6 +190,11 @@ enum bug_trap_type report_bug(unsigned l
                return BUG_TRAP_TYPE_WARN;
        }
 
+       if (kasan) {
+               __kasan_report(regs->di, regs->si, regs->dx, regs->cx);
+               return BUG_TRAP_TYPE_WARN;
+       }
+
        printk(KERN_DEFAULT CUT_HERE);
 
        if (file)
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -228,7 +228,7 @@ void __asan_unregister_globals(struct ka
 EXPORT_SYMBOL(__asan_unregister_globals);
 
 #define DEFINE_ASAN_LOAD_STORE(size)                                   \
-       void __asan_load##size(unsigned long addr)                      \
+       notrace void __asan_load##size(unsigned long addr)              \
        {                                                               \
                check_memory_region_inline(addr, size, false, _RET_IP_);\
        }                                                               \
@@ -236,7 +236,7 @@ EXPORT_SYMBOL(__asan_unregister_globals)
        __alias(__asan_load##size)                                      \
        void __asan_load##size##_noabort(unsigned long);                \
        EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
-       void __asan_store##size(unsigned long addr)                     \
+       notrace void __asan_store##size(unsigned long addr)             \
        {                                                               \
                check_memory_region_inline(addr, size, true, _RET_IP_); \
        }                                                               \
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -130,7 +130,7 @@ void check_memory_region(unsigned long a
 void *find_first_bad_addr(void *addr, size_t size);
 const char *get_bug_type(struct kasan_access_info *info);
 
-void kasan_report(unsigned long addr, size_t size,
+void __kasan_report(unsigned long addr, size_t size,
                bool is_write, unsigned long ip);
 void kasan_report_invalid_free(void *object, unsigned long ip);
 
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -281,7 +281,7 @@ void kasan_report_invalid_free(void *obj
        end_report(&flags);
 }
 
-void kasan_report(unsigned long addr, size_t size,
+void __kasan_report(unsigned long addr, size_t size,
                bool is_write, unsigned long ip)
 {
        struct kasan_access_info info;


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