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 6D6BC1D5144; Tue, 15 Oct 2024 13:15:19 +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=1728998119; cv=none; b=tzc0sHQ9DD3ZmN0duagYS5fQODjeM/BUtw4XCG/xeqVLatYVA9Z80j72UtE6mNUQGyCC402lHqNtTtW0Pl/icFzlCRJSDPzS7KtuwahUu1a6cda3hmtPPtjZ4jSj1rYxtS3s1FxJbuMKQiJrrGbTIh19k6ChY3VlqYwdC7N7Qco= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728998119; c=relaxed/simple; bh=RQWxDPVExIuO59pMtv5mfVOKod9f7GXQ9YAkaKMS2Og=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bDUvbG7H1IUYQpmcIkSnDuLCZ0jfvY0NDJN3Vd2gePsjKr94m3cBVVUn/eDtS4ZKXUGEg4JGKAHmNNdWMayvoAA+Cdl6cVMdHxSdT07Pqoxf01n7wXq5JTCv3xfenEUXGJ3D4e2nNAgZIPHDnlZSCzNM18vlCNxuKthLaxs+39o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sXbA9OlF; 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="sXbA9OlF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB7A8C4CEC6; Tue, 15 Oct 2024 13:15:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728998119; bh=RQWxDPVExIuO59pMtv5mfVOKod9f7GXQ9YAkaKMS2Og=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sXbA9OlF8ivOYPXHju0o84keaBgAAiM2iHGv63H9RAOAg2bI7rNPex279MCwsOUrc KWSNnC9qIWe+T35CfdyElJ6rAX1XkwUH3WPvSsMKSCL6S3tuMhvuDy0ySxR1/qnI2j 0d66+Rj9bZb4OjI+WRGdNql14R0T+A4Tb7DnTd7U= 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 5.10 385/518] mm: krealloc: consider spare memory for __GFP_ZERO Date: Tue, 15 Oct 2024 14:44:49 +0200 Message-ID: <20241015123931.829546036@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015123916.821186887@linuxfoundation.org> References: <20241015123916.821186887@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 5.10-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 @@ -1072,6 +1072,13 @@ static __always_inline void *__do_kreall ks = ksize(p); 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; }