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Tue, 13 Dec 2022 02:35:06 -0800 (PST) From: david.keisarschm@mail.huji.ac.il To: linux-kernel@vger.kernel.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: David , aksecurity@gmail.com, ilay.bahat1@gmail.com, linux-mm@kvack.org Subject: [PATCH v2 2/3] Replace invocation of weak PRNG inside mm/slab_common.c Date: Tue, 13 Dec 2022 12:34:58 +0200 Message-Id: X-Mailer: git-send-email 2.38.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 6E8418001A X-Stat-Signature: u8d4kp7za1b5tafkh6rfkc14bsj1r1a4 X-HE-Tag: 1670927708-223265 X-HE-Meta: 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 V4NIUNop xFt4NRfDp+IFXWxmEsghqVKQcrkg4lxHCInYKnjMeHwYRM1Ail7pSFbULSlWOiHCfwWOlH7J46hILFMQRWwPtIaDeucjeTSU1IqbHYqIpqHbDgtUEXtDHesVBPJffkto290aCYtI/0SN7wE+2SjF07kpP8WbKvITG8p2OPhGilOU6ndiEdSRLI0JHHsEH0hEMTAfI7pz7eof2HySWKiXLlRSoRDND7MS2FqassPYvtZCkvT6rIOM7rxtyiyQHqUToEUIBuUjSOpR4xVU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: David We changed the invocation of prandom_u32_state to get_random_u32. We also omitted the initial seeding for the state, since get_random_u32 maintains its own, so there is no need to keep storing the state of prandom_u32_state here. Signed-off-by: David --- mm/slab_common.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index b79755716..6ac68b9a6 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1130,7 +1130,7 @@ EXPORT_SYMBOL(kmalloc_large_node); #ifdef CONFIG_SLAB_FREELIST_RANDOM /* Randomize a generic freelist */ -static void freelist_randomize(struct rnd_state *state, unsigned int *list, +static void freelist_randomize(unsigned int *list, unsigned int count) { unsigned int rand; @@ -1141,7 +1141,7 @@ static void freelist_randomize(struct rnd_state *state, unsigned int *list, /* Fisher-Yates shuffle */ for (i = count - 1; i > 0; i--) { - rand = prandom_u32_state(state); + rand = get_random_u32(); rand %= (i + 1); swap(list[i], list[rand]); } @@ -1151,7 +1151,6 @@ static void freelist_randomize(struct rnd_state *state, unsigned int *list, int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, gfp_t gfp) { - struct rnd_state state; if (count < 2 || cachep->random_seq) return 0; @@ -1160,10 +1159,7 @@ int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, if (!cachep->random_seq) return -ENOMEM; - /* Get best entropy at this stage of boot */ - prandom_seed_state(&state, get_random_long()); - - freelist_randomize(&state, cachep->random_seq, count); + freelist_randomize(cachep->random_seq, count); return 0; } -- 2.38.0