From: Jann Horn <jannh@google.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, jannh@google.com
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] x86/mtrr: don't copy out-of-bounds data in mtrr_write
Date: Fri, 6 Jul 2018 23:50:03 +0200
Message-ID: <20180706215003.156702-1-jannh@google.com> (raw)
Don't access the provided buffer out of bounds - this can cause a kernel
out-of-bounds read when invoked through sys_splice() or other things that
use kernel_write()/__kernel_write().
Fixes: 7f8ec5a4f01a ("x86/mtrr: Convert to use strncpy_from_user() helper")
Signed-off-by: Jann Horn <jannh@google.com>
---
arch/x86/kernel/cpu/mtrr/if.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c
index 4021d3859499..40eee6cc4124 100644
--- a/arch/x86/kernel/cpu/mtrr/if.c
+++ b/arch/x86/kernel/cpu/mtrr/if.c
@@ -106,7 +106,8 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
memset(line, 0, LINE_SIZE);
- length = strncpy_from_user(line, buf, LINE_SIZE - 1);
+ len = min_t(size_t, len, LINE_SIZE - 1);
+ length = strncpy_from_user(line, buf, len);
if (length < 0)
return length;
--
2.18.0.203.gfac676dfb9-goog
next reply index
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 21:50 Jann Horn [this message]
2018-07-07 17:04 ` [tip:x86/urgent] x86/mtrr: Don't " tip-bot for Jann Horn
2018-07-09 6:52 ` [PATCH] x86/mtrr: don't " Andy Shevchenko
2018-07-09 7:41 ` Jann Horn
2018-07-09 8:20 ` Andy Shevchenko
2018-07-15 22:03 ` Ingo Molnar
2018-07-16 1:32 ` Jann Horn
2018-07-16 1:46 ` Linus Torvalds
2018-07-16 2:26 ` Al Viro
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180706215003.156702-1-jannh@google.com \
--to=jannh@google.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
LKML Archive on lore.kernel.org
Archives are clonable:
git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
linux-kernel@vger.kernel.org
public-inbox-index lkml
Example config snippet for mirrors
Newsgroup available over NNTP:
nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git