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From: Christoph Hellwig <hch@lst.de>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Vegard Nossum <vegard.nossum@oracle.com>
Subject: [PATCH 2/2] sysctl: reject gigantic reads/write to sysctl files
Date: Tue,  9 Jun 2020 19:08:19 +0200	[thread overview]
Message-ID: <20200609170819.52353-3-hch@lst.de> (raw)
In-Reply-To: <20200609170819.52353-1-hch@lst.de>

Instead of triggering a WARN_ON deep down in the page allocator just
give up early on allocations that are way larger than the usual sysctl
values.

Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler")
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/proc/proc_sysctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index df2143e05c571e..08c33bd1642dcd 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -564,6 +564,10 @@ static ssize_t proc_sys_call_handler(struct file *filp, void __user *ubuf,
 	if (!table->proc_handler)
 		goto out;
 
+	/* don't even try if the size is too large */
+	if (count > KMALLOC_MAX_SIZE)
+		return -ENOMEM;
+
 	if (write) {
 		kbuf = memdup_user_nul(ubuf, count);
 		if (IS_ERR(kbuf)) {
-- 
2.26.2


  parent reply	other threads:[~2020-06-09 17:15 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-09 17:08 two more fixes for sysctl Christoph Hellwig
2020-06-09 17:08 ` [PATCH 1/2] cdrom: fix an incorrect __user annotation on cdrom_sysctl_info Christoph Hellwig
2020-06-09 17:08 ` Christoph Hellwig [this message]
2020-06-09 17:30 ` two more fixes for sysctl Luis Chamberlain
2020-06-10  4:28 ` Al Viro

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