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-next>] [day] [month] [year] [list]
Message-ID: <ZItSlzvIpjdjNfd8@work>
Date: Thu, 15 Jun 2023 12:04:07 -0600
From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
To: Johannes Berg <johannes@...solutions.net>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-hardening@...r.kernel.org
Subject: [PATCH][next] wifi: wext-core: Fix -Wstringop-overflow warning in
 ioctl_standard_iw_point()

-Wstringop-overflow is legitimately warning us about extra_size
pontentially being zero at some point, hence potenially ending
up _allocating_ zero bytes of memory for extra pointer and then
trying to access such object in a call to copy_from_user().

Fix this by adding a sanity check to ensure we never end up
trying to allocate zero bytes of data for extra pointer, before
continue executing the rest of the code in the function.

Address the following -Wstringop-overflow warning seen when built
m68k architecture with allyesconfig configuration:
                 from net/wireless/wext-core.c:11:
In function '_copy_from_user',
    inlined from 'copy_from_user' at include/linux/uaccess.h:183:7,
    inlined from 'ioctl_standard_iw_point' at net/wireless/wext-core.c:825:7:
arch/m68k/include/asm/string.h:48:25: warning: '__builtin_memset' writing 1 or more bytes into a region of size 0 overflows the destination [-Wstringop-overflow=]
   48 | #define memset(d, c, n) __builtin_memset(d, c, n)
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:153:17: note: in expansion of macro 'memset'
  153 |                 memset(to + (n - res), 0, res);
      |                 ^~~~~~
In function 'kmalloc',
    inlined from 'kzalloc' at include/linux/slab.h:694:9,
    inlined from 'ioctl_standard_iw_point' at net/wireless/wext-core.c:819:10:
include/linux/slab.h:577:16: note: at offset 1 into destination object of size 0 allocated by '__kmalloc'
  577 |         return __kmalloc(size, flags);
      |                ^~~~~~~~~~~~~~~~~~~~~~

This help with the ongoing efforts to globally enable
-Wstringop-overflow.

Link: https://github.com/KSPP/linux/issues/315
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 net/wireless/wext-core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
index a125fd1fa134..a161c64d1765 100644
--- a/net/wireless/wext-core.c
+++ b/net/wireless/wext-core.c
@@ -815,6 +815,12 @@ static int ioctl_standard_iw_point(struct iw_point *iwp, unsigned int cmd,
 		}
 	}
 
+	/* Sanity-check to ensure we never end up _allocating_ zero
+	 * bytes of data for extra.
+	 */
+	if (extra_size <= 0)
+		return -EFAULT;
+
 	/* kzalloc() ensures NULL-termination for essid_compat. */
 	extra = kzalloc(extra_size, GFP_KERNEL);
 	if (!extra)
-- 
2.34.1


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ