In dentry_string_cmp (via__d_lookup_rcu), when CONFIG_DCACHE_WORD_ACCESS is set, word-width memory reads are performed. However, the string allocation size may not be a multiple of the word size. To avoid reading past the end of such an allocation, we must allocate in multiples of the word size.
Found by the Kernel Address Sanitizer project: https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel Reported-by: Dmitry Vyukov <dvyu...@google.com> Signed-off-by: Kees Cook <keesc...@chromium.org> --- fs/dcache.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/dcache.c b/fs/dcache.c index 4100030..23665e2 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1570,7 +1570,11 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) */ dentry->d_iname[DNAME_INLINE_LEN-1] = 0; if (name->len > DNAME_INLINE_LEN-1) { - dname = kmalloc(name->len + 1, GFP_KERNEL); + size_t alloc_size = name->len + 1; +#ifdef CONFIG_DCACHE_WORD_ACCESS + alloc_size = round_up(alloc_size, sizeof(unsigned long)); +#endif + dname = kmalloc(alloc_size, GFP_KERNEL); if (!dname) { kmem_cache_free(dentry_cache, dentry); return NULL; -- 1.7.9.5 -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
