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    Subject[RFC/PATCH -next 20/21] fs: dcache: manually unpoison dname after allocation to shut up kasan's reports
    Date
    We need to manually unpoison rounded up allocation size for dname
    to avoid kasan's reports in __d_lookup_rcu.
    __d_lookup_rcu may validly read a little beyound allocated size.

    Reported-by: Dmitry Vyukov <dvyukov@google.com>
    Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
    ---
    fs/dcache.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/fs/dcache.c b/fs/dcache.c
    index b7e8b20..dff64f2 100644
    --- a/fs/dcache.c
    +++ b/fs/dcache.c
    @@ -38,6 +38,7 @@
    #include <linux/prefetch.h>
    #include <linux/ratelimit.h>
    #include <linux/list_lru.h>
    +#include <linux/kasan.h>
    #include "internal.h"
    #include "mount.h"

    @@ -1412,6 +1413,8 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
    kmem_cache_free(dentry_cache, dentry);
    return NULL;
    }
    + unpoison_shadow(dname,
    + roundup(name->len + 1, sizeof(unsigned long)));
    } else {
    dname = dentry->d_iname;
    }
    --
    1.8.5.5


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