From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E39CE1AE01F; Mon, 14 Oct 2024 15:22:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728919376; cv=none; b=sfl4oO8WEKMnWdOS9dOd4qvh5dMjA/waxU61edeuQ5tB2KBEY+bP1V4OCi1ByJ3dy8zZ9e21lO8rfhLByw4pq4M7KHC9K43wEoqYRiqM3nn5X/eoL+nnN4rTfYxTZUIe9beVbRVqtDrFYS4QdHcUEB00aTgVBS+aA9OYyNfyT8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728919376; c=relaxed/simple; bh=oPk4u5WjiJ/ecqFm/sdGg/MMdzhuuEDK/ft7rgI06EM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mCNLmwvUkNtjyLIgVHyjYAAZAZerJXolKHxX+CIZl1ovAE3uF6ppLTqZBuR63sHRl7MGcv6meHzfyAaXnlu7o9d+fkstL23F4x9oLgiDFFGMcuZ5R57PwOSdbamZuq4+iYNI7p2X/Gxk/+AUjH6ace0hyV7+/i6qOmKlWMXoAsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=INpsGBeG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="INpsGBeG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE411C4CEC3; Mon, 14 Oct 2024 15:22:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728919375; bh=oPk4u5WjiJ/ecqFm/sdGg/MMdzhuuEDK/ft7rgI06EM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=INpsGBeGKj5pdvPJ70C7WIeVgPkTiR37k9Gmyh5jKHRS60KCwYrH34xK3/ySA5CNi uZX31IknLJmWclIN2vBrMjUNYYaVT8e605nUp8rroOiMA9fGUA7L2wKp8sy7xpM8b+ 82GGizMeYPircd9sOIZF05szSSGvQwZoQvv0nkB4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Danilo Krummrich , Vlastimil Babka , David Rientjes , Christoph Lameter , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Joonsoo Kim , Pekka Enberg , Roman Gushchin , Andrew Morton Subject: [PATCH 6.1 565/798] mm: krealloc: consider spare memory for __GFP_ZERO Date: Mon, 14 Oct 2024 16:18:39 +0200 Message-ID: <20241014141240.194585562@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241014141217.941104064@linuxfoundation.org> References: <20241014141217.941104064@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Danilo Krummrich commit 1a83a716ec233990e1fd5b6fbb1200ade63bf450 upstream. As long as krealloc() is called with __GFP_ZERO consistently, starting with the initial memory allocation, __GFP_ZERO should be fully honored. However, if for an existing allocation krealloc() is called with a decreased size, it is not ensured that the spare portion the allocation is zeroed. Thus, if krealloc() is subsequently called with a larger size again, __GFP_ZERO can't be fully honored, since we don't know the previous size, but only the bucket size. Example: buf = kzalloc(64, GFP_KERNEL); memset(buf, 0xff, 64); buf = krealloc(buf, 48, GFP_KERNEL | __GFP_ZERO); /* After this call the last 16 bytes are still 0xff. */ buf = krealloc(buf, 64, GFP_KERNEL | __GFP_ZERO); Fix this, by explicitly setting spare memory to zero, when shrinking an allocation with __GFP_ZERO flag set or init_on_alloc enabled. Link: https://lkml.kernel.org/r/20240812223707.32049-1-dakr@kernel.org Signed-off-by: Danilo Krummrich Acked-by: Vlastimil Babka Acked-by: David Rientjes Cc: Christoph Lameter Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Pekka Enberg Cc: Roman Gushchin Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/slab_common.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1322,6 +1322,13 @@ __do_krealloc(const void *p, size_t new_ /* If the object still fits, repoison it precisely. */ if (ks >= new_size) { + /* Zero out spare memory. */ + if (want_init_on_alloc(flags)) { + kasan_disable_current(); + memset((void *)p + new_size, 0, ks - new_size); + kasan_enable_current(); + } + p = kasan_krealloc((void *)p, new_size, flags); return (void *)p; }