| From | Andrey Ryabinin <> | Subject | [PATCH v6 09/11] fs: dcache: manually unpoison dname after allocation to shut up kasan's reports | Date | Wed, 05 Nov 2014 17:53:59 +0300 |
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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 <dvyukov@google.com> Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> --- fs/dcache.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/dcache.c b/fs/dcache.c index d5a23fd..d58ffcc6 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
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