[3/3] btrfs: tree-checker: Avoid accidental stack VLA
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Message ID 1520479847-39174-4-git-send-email-keescook@chromium.org
State New
Headers show

Commit Message

Kees Cook March 8, 2018, 3:30 a.m. UTC
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(-)

Comments

David Sterba March 8, 2018, 11:33 a.m. UTC | #1
On Wed, Mar 07, 2018 at 07:30:47PM -0800, Kees Cook wrote:
> 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>

Acked-by: David Sterba <dsterba@suse.com>

for whatever name you decide for the max macro.
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Patch
diff mbox

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);