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R . Silva" , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] xen/gntalloc: Replace UAPI 1-element array Date: Tue, 6 Feb 2024 09:03:24 -0800 Message-Id: <20240206170320.work.437-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1659; i=keescook@chromium.org; h=from:subject:message-id; bh=U8HuNwUdlEEPLHdv3QRnH+uJMA60aHmIoxCx5CgE2PE=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlwmZc1Jfxj5fa/YwMvoyvAPkFWN+gRJLJEPn7F n308vxItD6JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZcJmXAAKCRCJcvTf3G3A Jm0GD/oDXr7gvAa43q/4w9dV1f3MZINBzTm2QNk9mHvC7Lp7XSOmcgrCG2Fi8o4c5s5TyWIybl8 slT25ToB1KNPSc6IPGYoFcQTXwRn39TzQq9T6n+5z5alG6Bz6ZcAk34BQcIm6vfpD3/N11fHF5F pdXab4HtiJd2JS9uhggiaHQbN59FGqFQjmpFiouIQ/v5r3awL2QgSC+DznPmZAbee6vD1Rz7G3F Ko9yltkr64NVBYCrLDQEylWIDjzGcaMn7kb9npaAYzOCcDcDcQgyfA41idDc+YZlQhxJhuTBe+h kHCag8yYsbha7fMXGE+7jHPzjKzE92858eEHiqDJUS+n7u5FMMzarLFrfzeX2LRKJT3oKVKLNhA pZ8OYm0q7YJihVOtzaWRo2aNTZ1TpHpDtp7xQo0UFmVh8lcE8p41nIm3bKoC/PbT6ygufKRWEgT F1cqwtPM+91yYdVb5HqaHdJ1hIahqo84hQrS6uoeJb2fDi7VWnvopFiUKfVEjWhqUqDo4DCatRo 9wGXoVt2ljvrVqDQoE56vPuRpeLfSDuLDp/koDL82+UGsSCzmRyXeFrADIlakadryKPFCIqd6xf eyoiFXJ0khVBIixLTkPKRY4vvEmldd97HWkoEuj0POSSL7w/8LzGaHlA9x8qqoGsFQwQ6Uvf4U+ Vekxg2a ltTDiLAQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Without changing the structure size (since it is UAPI), add a proper flexible array member, and reference it in the kernel so that it will not be trip the array-bounds sanitizer[1]. Link: https://github.com/KSPP/linux/issues/113 [1] Cc: Juergen Gross Cc: Stefano Stabellini Cc: Oleksandr Tyshchenko Cc: Gustavo A. R. Silva Cc: xen-devel@lists.xenproject.org Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva --- drivers/xen/gntalloc.c | 2 +- include/uapi/xen/gntalloc.h | 5 ++++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c index 26ffb8755ffb..f93f73ecefee 100644 --- a/drivers/xen/gntalloc.c +++ b/drivers/xen/gntalloc.c @@ -317,7 +317,7 @@ static long gntalloc_ioctl_alloc(struct gntalloc_file_private_data *priv, rc = -EFAULT; goto out_free; } - if (copy_to_user(arg->gref_ids, gref_ids, + if (copy_to_user(arg->gref_ids_flex, gref_ids, sizeof(gref_ids[0]) * op.count)) { rc = -EFAULT; goto out_free; diff --git a/include/uapi/xen/gntalloc.h b/include/uapi/xen/gntalloc.h index 48d2790ef928..3109282672f3 100644 --- a/include/uapi/xen/gntalloc.h +++ b/include/uapi/xen/gntalloc.h @@ -31,7 +31,10 @@ struct ioctl_gntalloc_alloc_gref { __u64 index; /* The grant references of the newly created grant, one per page */ /* Variable size, depending on count */ - __u32 gref_ids[1]; + union { + __u32 gref_ids[1]; + __DECLARE_FLEX_ARRAY(__u32, gref_ids_flex); + }; }; #define GNTALLOC_FLAG_WRITABLE 1