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From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org, corbet@lwn.net,
	gustavo@embeddedor.com, rostedt@goodmis.org,
	Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
	David Sterba <dsterba@suse.com>,
	"David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Borislav Petkov <bp@suse.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Ian Abbott <abbotti@mev.co.uk>, "Tobin C. Harding" <me@tobin.cc>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	linux-btrfs@vger.kernel.org, netdev@vger.kernel.org,
	kernel-hardening@lists.openwall.com
Subject: [PATCH 3/3] btrfs: tree-checker: Avoid accidental stack VLA
Date: Wed,  7 Mar 2018 19:30:47 -0800	[thread overview]
Message-ID: <1520479847-39174-4-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1520479847-39174-1-git-send-email-keescook@chromium.org>

In the quest to remove all stack VLAs from the kernel[1], this refactors
the stack array size calculation to avoid using max(), which makes the
compiler think the size isn't fixed.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/btrfs/tree-checker.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index c3c8d48f6618..59bd07694118 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -341,7 +341,8 @@ static int check_dir_item(struct btrfs_root *root,
 		 */
 		if (key->type == BTRFS_DIR_ITEM_KEY ||
 		    key->type == BTRFS_XATTR_ITEM_KEY) {
-			char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+			char namebuf[SIMPLE_MAX(BTRFS_NAME_LEN,
+						XATTR_NAME_MAX)];
 
 			read_extent_buffer(leaf, namebuf,
 					(unsigned long)(di + 1), name_len);
-- 
2.7.4


WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	linux-kernel@vger.kernel.org, corbet@lwn.net,
	gustavo@embeddedor.com, rostedt@goodmis.org,
	Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
	David Sterba <dsterba@suse.com>,
	"David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Borislav Petkov <bp@suse.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Ian Abbott <abbotti@mev.co.uk>, "Tobin C. Harding" <me@tobin.cc>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	linux-bt
Subject: [PATCH 3/3] btrfs: tree-checker: Avoid accidental stack VLA
Date: Wed,  7 Mar 2018 19:30:47 -0800	[thread overview]
Message-ID: <1520479847-39174-4-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1520479847-39174-1-git-send-email-keescook@chromium.org>

In the quest to remove all stack VLAs from the kernel[1], this refactors
the stack array size calculation to avoid using max(), which makes the
compiler think the size isn't fixed.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/btrfs/tree-checker.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index c3c8d48f6618..59bd07694118 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -341,7 +341,8 @@ static int check_dir_item(struct btrfs_root *root,
 		 */
 		if (key->type == BTRFS_DIR_ITEM_KEY ||
 		    key->type == BTRFS_XATTR_ITEM_KEY) {
-			char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+			char namebuf[SIMPLE_MAX(BTRFS_NAME_LEN,
+						XATTR_NAME_MAX)];
 
 			read_extent_buffer(leaf, namebuf,
 					(unsigned long)(di + 1), name_len);
-- 
2.7.4

  parent reply	other threads:[~2018-03-08  3:31 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-08  3:30 [PATCH 0/3] Remove accidental VLA usage Kees Cook
2018-03-08  3:30 ` Kees Cook
2018-03-08  3:30 ` [PATCH v2 1/3] vsprintf: " Kees Cook
2018-03-08  3:30   ` Kees Cook
2018-03-08  8:25   ` Rasmus Villemoes
2018-03-08  8:25     ` Rasmus Villemoes
2018-03-08 11:21     ` Thomas Gleixner
2018-03-08 11:21       ` Thomas Gleixner
2018-03-08  3:30 ` [PATCH 2/3] net: Remove accidental VLAs from proc buffers Kees Cook
2018-03-08  3:30   ` Kees Cook
2018-03-08  3:30 ` Kees Cook [this message]
2018-03-08  3:30   ` [PATCH 3/3] btrfs: tree-checker: Avoid accidental stack VLA Kees Cook
2018-03-08 11:33   ` David Sterba
2018-03-08 11:33     ` David Sterba
2018-03-08 15:02 ` [PATCH 0/3] Remove accidental VLA usage Josh Poimboeuf
2018-03-08 15:02   ` Josh Poimboeuf
2018-03-08 18:02   ` Kees Cook
2018-03-08 18:02     ` Kees Cook
2018-03-08 18:11     ` Josh Poimboeuf
2018-03-08 18:11       ` Josh Poimboeuf
2018-03-08 18:06   ` Steven Rostedt
2018-03-08 18:06     ` Steven Rostedt
2018-03-08 19:57   ` Rasmus Villemoes
2018-03-08 19:57     ` Rasmus Villemoes
2018-03-08 20:39     ` Kees Cook
2018-03-08 20:39       ` Kees Cook
2018-03-08 22:12       ` Rasmus Villemoes
2018-03-08 22:12         ` Rasmus Villemoes
2018-03-08 23:33         ` Kees Cook
2018-03-08 23:33           ` Kees Cook
2018-03-08 20:49   ` Andrew Morton
2018-03-08 20:49     ` Andrew Morton

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