Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> writes: > MODULE_DEVICE_TABLE() macro used to create aliases to device tables. > Normally alias should have the same type as aliased symbol. > > Device tables are arrays, so they have 'struct type##_device_id[x]' > types. Alias created by MODULE_DEVICE_TABLE() will have non-array type - > 'struct type##_device_id'. > > This inconsistency confuses compiler, it could make a wrong > assumption about variable's size which leads KASan to > produce a false positive report about out of bounds access. Hmm, as Andrew Morton points out, this breaks some usage; if we just fix the type (struct type##_device_id[]) will that work instead? I'm guessing not, since typeof(x) will presumably preserve sizing information? Cheers, Rusty. > > For every global variable compiler calls __asan_register_globals() > passing information about global variable (address, size, size with > redzone, name ...) __asan_register_globals() poison symbols > redzone to detect possible out of bounds accesses. > > When symbol has an alias __asan_register_globals() will be called > as for symbol so for alias. Compiler determines size of variable by > size of variable's type. Alias and symbol have the same address, > so if alias have the wrong size part of memory that actually belongs > to the symbol could be poisoned as redzone of alias symbol. > > By fixing type of alias symbol we will fix size of it, so > __asan_register_globals() will not poison valid memory. > > Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> > --- > include/linux/module.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/module.h b/include/linux/module.h > index b653d7c..42999fe 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -135,7 +135,7 @@ void trim_init_extable(struct module *m); > #ifdef MODULE > /* Creates an alias so file2alias.c can find device table. */ > #define MODULE_DEVICE_TABLE(type, name) \ > - extern const struct type##_device_id __mod_##type##__##name##_device_table \ > +extern const typeof(name) __mod_##type##__##name##_device_table \ > __attribute__ ((unused, alias(__stringify(name)))) > #else /* !MODULE */ > #define MODULE_DEVICE_TABLE(type, name) > -- > 2.2.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>