linux-kernel - [PATCH] tomoyo: don't emit warning in tomoyo_write

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 linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <57f7253d-a55e-420a-b1b1-f572a0ab13f2@I-love.SAKURA.ne.jp>
Date: Mon, 16 Dec 2024 19:45:06 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: syzbot <syzbot+7536f77535e5210a5c76@...kaller.appspotmail.com>,
        jmorris@...ei.org, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org, paul@...l-moore.com,
        serge@...lyn.com, syzkaller-bugs@...glegroups.com,
        takedakn@...data.co.jp, Leo Stone <leocstone@...il.com>
Subject: [PATCH] tomoyo: don't emit warning in tomoyo_write_control()

syzbot is reporting too large allocation warning at tomoyo_write_control(),
for one can write a very very long line without new line character. To fix
this warning, I use __GFP_NOWARN rather than checking for KMALLOC_MAX_SIZE,
for practically a valid line should be always shorter than 32KB where the
"too small to fail" memory-allocation rule applies.

One might try to write a valid line that is longer than 32KB, but such
request will likely fail with -ENOMEM. Therefore, I feel that separately
returning -EINVAL when a line is longer than KMALLOC_MAX_SIZE is redundant.
There is no need to distinguish over-32KB and over-KMALLOC_MAX_SIZE.

Reported-by: syzbot+7536f77535e5210a5c76@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7536f77535e5210a5c76
Reported-by: Leo Stone <leocstone@...il.com>
Closes: https://lkml.kernel.org/r/20241216021459.178759-2-leocstone@gmail.com
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 security/tomoyo/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 5c7b059a332a..972664962e8f 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -2665,7 +2665,7 @@ ssize_t tomoyo_write_control(struct tomoyo_io_buffer *head,

 		if (head->w.avail >= head->writebuf_size - 1) {
 			const int len = head->writebuf_size * 2;
-			char *cp = kzalloc(len, GFP_NOFS);
+			char *cp = kzalloc(len, GFP_NOFS | __GFP_NOWARN);

 			if (!cp) {
 				error = -ENOMEM;
-- 
2.43.5