We need to manually unpoison rounded up allocation size for dname to avoid kasan's reports in dentry_string_cmp(). When CONFIG_DCACHE_WORD_ACCESS=y dentry_string_cmp may access few bytes beyound requested in kmalloc() size.
dentry_string_cmp() relates on that fact that dentry allocated using kmalloc and kmalloc internally round up allocation size. So this is not a bug, but this makes kasan to complain about such accesses. To avoid such reports we mark rounded up allocation size in shadow as accessible. Reported-by: Dmitry Vyukov <[email protected]> Signed-off-by: Andrey Ryabinin <[email protected]> --- fs/dcache.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index a6c5d7e..3914e56 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -38,6 +38,8 @@ #include <linux/prefetch.h> #include <linux/ratelimit.h> #include <linux/list_lru.h> +#include <linux/kasan.h> + #include "internal.h" #include "mount.h" @@ -1429,6 +1431,10 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) } atomic_set(&p->u.count, 1); dname = p->name; +#ifdef CONFIG_DCACHE_WORD_ACCESS + kasan_unpoison_shadow(dname, + round_up(name->len + 1, sizeof(unsigned long))); +#endif } else { dname = dentry->d_iname; } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
