lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 21 Sep 2022 20:10:05 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Kees Cook <keescook@...omium.org>, linux-btrfs@...r.kernel.org,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Alex Elder <elder@...nel.org>,
        Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian K├Ânig <christian.koenig@....com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Daniel Micay <danielmicay@...il.com>,
        Yonghong Song <yhs@...com>, Marco Elver <elver@...gle.com>,
        Miguel Ojeda <ojeda@...nel.org>,
        Jacob Shin <jacob.shin@....com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, netdev@...r.kernel.org,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-fsdevel@...r.kernel.org,
        intel-wired-lan@...ts.osuosl.org, dev@...nvswitch.org,
        x86@...nel.org, linux-wireless@...r.kernel.org,
        llvm@...ts.linux.dev, linux-hardening@...r.kernel.org
Subject: [PATCH 04/12] btrfs: send: Proactively round up to kmalloc bucket size

Instead of discovering the kmalloc bucket size _after_ allocation, round
up proactively so the allocation is explicitly made for the full size,
allowing the compiler to correctly reason about the resulting size of
the buffer through the existing __alloc_size() hint.

Cc: linux-btrfs@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/btrfs/send.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index e7671afcee4f..d40d65598e8f 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -435,6 +435,11 @@ static int fs_path_ensure_buf(struct fs_path *p, int len)
 	path_len = p->end - p->start;
 	old_buf_len = p->buf_len;
 
+	/*
+	 * Allocate to the next largest kmalloc bucket size, to let
+	 * the fast path happen most of the time.
+	 */
+	len = kmalloc_size_roundup(len);
 	/*
 	 * First time the inline_buf does not suffice
 	 */
@@ -448,11 +453,7 @@ static int fs_path_ensure_buf(struct fs_path *p, int len)
 	if (!tmp_buf)
 		return -ENOMEM;
 	p->buf = tmp_buf;
-	/*
-	 * The real size of the buffer is bigger, this will let the fast path
-	 * happen most of the time
-	 */
-	p->buf_len = ksize(p->buf);
+	p->buf_len = len;
 
 	if (p->reversed) {
 		tmp_buf = p->buf + old_buf_len - path_len - 1;
-- 
2.34.1

Powered by blists - more mailing lists