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From: Arnd Bergmann <arnd@kernel.org>
To: linux-kernel@vger.kernel.org, Martin Sebor <msebor@gcc.gnu.org>,
	Anders Larsen <al@alarsen.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
	x86@kernel.org, Ning Sun <ning.sun@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Kalle Valo <kvalo@codeaurora.org>,
	Simon Kelley <simon@thekelleys.org.uk>,
	James Smart <james.smart@broadcom.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	Tejun Heo <tj@kernel.org>, Serge Hallyn <serge@hallyn.com>,
	Imre Deak <imre.deak@intel.com>,
	linux-arm-kernel@lists.infradead.org,
	tboot-devel@lists.sourceforge.net,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, linux-scsi@vger.kernel.org,
	cgroups@vger.kernel.org, linux-security-module@vger.kernel.org
Subject: [PATCH 05/11] qnx: avoid -Wstringop-overread warning
Date: Mon, 22 Mar 2021 17:02:43 +0100
Message-ID: <20210322160253.4032422-6-arnd@kernel.org> (raw)
In-Reply-To: <20210322160253.4032422-1-arnd@kernel.org>

From: Arnd Bergmann <arnd@arndb.de>

gcc-11 warns that the size of the link name is longer than the di_fname
field:

fs/qnx4/dir.c: In function ‘qnx4_readdir’:
fs/qnx4/dir.c:51:32: error: ‘strnlen’ specified bound 48 exceeds source size 16 [-Werror=stringop-overread]
   51 |                         size = strnlen(de->di_fname, size);
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from fs/qnx4/qnx4.h:3,
                 from fs/qnx4/dir.c:16:
include/uapi/linux/qnx4_fs.h:45:25: note: source object declared here
   45 |         char            di_fname[QNX4_SHORT_NAME_MAX];

The problem here is that we access the same pointer using two different
structure layouts, but gcc determines the object size based on
whatever it encounters first.

Change the strnlen to use the correct field size in each case, and
change the first access to be on the longer field.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 fs/qnx4/dir.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
index a6ee23aadd28..68046450e543 100644
--- a/fs/qnx4/dir.c
+++ b/fs/qnx4/dir.c
@@ -39,21 +39,20 @@ static int qnx4_readdir(struct file *file, struct dir_context *ctx)
 		ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
 		for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
 			offset = ix * QNX4_DIR_ENTRY_SIZE;
-			de = (struct qnx4_inode_entry *) (bh->b_data + offset);
-			if (!de->di_fname[0])
+			le = (struct qnx4_link_info *)(bh->b_data + offset);
+			de = (struct qnx4_inode_entry *)(bh->b_data + offset);
+			if (!le->dl_fname[0])
 				continue;
 			if (!(de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
 				continue;
 			if (!(de->di_status & QNX4_FILE_LINK))
-				size = QNX4_SHORT_NAME_MAX;
+				size = strnlen(de->di_fname, sizeof(de->di_fname));
 			else
-				size = QNX4_NAME_MAX;
-			size = strnlen(de->di_fname, size);
+				size = strnlen(le->dl_fname, sizeof(le->dl_fname));
 			QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, de->di_fname));
 			if (!(de->di_status & QNX4_FILE_LINK))
 				ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
 			else {
-				le  = (struct qnx4_link_info*)de;
 				ino = ( le32_to_cpu(le->dl_inode_blk) - 1 ) *
 					QNX4_INODES_PER_BLOCK +
 					le->dl_inode_ndx;
-- 
2.29.2


  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-22 16:02 [PATCH 00/11] treewide: address gcc-11 -Wstringop-overread warnings Arnd Bergmann
2021-03-22 16:02 ` [PATCH 01/11] x86: compressed: avoid gcc-11 -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02 ` [PATCH 02/11] x86: tboot: avoid Wstringop-overread-warning Arnd Bergmann
2021-03-22 20:29   ` Ingo Molnar
2021-03-22 21:39     ` Arnd Bergmann
2021-03-22 22:07     ` Martin Sebor
2021-03-22 22:49       ` Arnd Bergmann
2021-03-22 23:13       ` Ingo Molnar
2021-03-24  9:11       ` David Laight
2021-03-24 10:39         ` David Laight
2021-03-22 16:02 ` [PATCH 03/11] security: commoncap: fix -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:31   ` Christian Brauner
2021-03-24 20:50   ` James Morris
2021-03-22 16:02 ` [PATCH 04/11] ath11: Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02 ` Arnd Bergmann [this message]
2021-03-22 16:02 ` [PATCH 06/11] cgroup: fix -Wzero-length-bounds warnings Arnd Bergmann
2021-03-30  8:41   ` Michal Koutný
2021-03-30  9:00     ` Arnd Bergmann
2021-03-30 14:44       ` Michal Koutný
2021-03-22 16:02 ` [PATCH 07/11] ARM: sharpsl_param: work around -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02 ` [PATCH 08/11] atmel: avoid gcc -Wstringop-overflow warning Arnd Bergmann
2021-03-22 16:02 ` [PATCH 09/11] scsi: lpfc: fix gcc -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02 ` [PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency Arnd Bergmann
2021-03-24 15:30   ` Jani Nikula
2021-03-24 17:22     ` Ville Syrjälä
2021-03-22 16:02 ` [PATCH 11/11] [RFC] drm/i915/dp: fix array overflow warning Arnd Bergmann
2021-03-25  8:05   ` Jani Nikula
2021-03-25  9:53     ` Arnd Bergmann
2021-03-25 14:49       ` Martin Sebor
2021-03-30 10:56   ` Hans de Goede
2021-04-06  4:53 ` [PATCH 00/11] treewide: address gcc-11 -Wstringop-overread warnings Martin K. Petersen

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