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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Daniel Vetter <daniel.vetter@intel.com>,
        syzbot+fb77e97ebf0612ee6914@syzkaller.appspotmail.com,
        Kees Cook <keescook@chromium.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 5.4 145/191] drm: limit to INT_MAX in create_blob ioctl
Date:   Thu,  2 Jan 2020 23:07:07 +0100
Message-Id: <20200102215845.053049824@linuxfoundation.org>
In-Reply-To: <20200102215829.911231638@linuxfoundation.org>
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From: Daniel Vetter <daniel.vetter@ffwll.ch>

commit 5bf8bec3f4ce044a223c40cbce92590d938f0e9c upstream.

The hardened usercpy code is too paranoid ever since commit 6a30afa8c1fb
("uaccess: disallow > INT_MAX copy sizes")

Code itself should have been fine as-is.

Link: http://lkml.kernel.org/r/20191106164755.31478-1-daniel.vetter@ffwll.ch
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reported-by: syzbot+fb77e97ebf0612ee6914@syzkaller.appspotmail.com
Fixes: 6a30afa8c1fb ("uaccess: disallow > INT_MAX copy sizes")
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_property.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -561,7 +561,7 @@ drm_property_create_blob(struct drm_devi
 	struct drm_property_blob *blob;
 	int ret;
 
-	if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
+	if (!length || length > INT_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
 	blob = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);