From acafe7e30216166a17e6e226aadc3ecb63993242 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 8 May 2018 13:45:50 -0700 Subject: treewide: Use struct_size() for kmalloc()-family One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; void *entry[]; }; instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL); This patch makes the changes for kmalloc()-family (and kvmalloc()-family) uses. It was done via automatic conversion with manual review for the "CHECKME" non-standard cases noted below, using the following Coccinelle script: // pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len * // sizeof *pkey_cache->table, GFP_KERNEL); @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; identifier VAR, ELEMENT; expression COUNT; @@ - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP) + alloc(struct_size(VAR, ELEMENT, COUNT), GFP) // mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL); @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; identifier VAR, ELEMENT; expression COUNT; @@ - alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP) + alloc(struct_size(VAR, ELEMENT, COUNT), GFP) // Same pattern, but can't trivially locate the trailing element name, // or variable name. @@ identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc"; expression GFP; expression SOMETHING, COUNT, ELEMENT; @@ - alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP) + alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP) Signed-off-by: Kees Cook --- kernel/cgroup/cgroup.c | 4 ++-- kernel/module.c | 3 +-- kernel/workqueue.c | 3 +-- 3 files changed, 4 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index a662bfcbea0e..2238661bf878 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4775,8 +4775,8 @@ static struct cgroup *cgroup_create(struct cgroup *parent) int ret; /* allocate the cgroup and its ID, 0 is reserved for the root */ - cgrp = kzalloc(sizeof(*cgrp) + - sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL); + cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)), + GFP_KERNEL); if (!cgrp) return ERR_PTR(-ENOMEM); diff --git a/kernel/module.c b/kernel/module.c index ce8066b88178..307272679a55 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1604,8 +1604,7 @@ static void add_notes_attrs(struct module *mod, const struct load_info *info) if (notes == 0) return; - notes_attrs = kzalloc(sizeof(*notes_attrs) - + notes * sizeof(notes_attrs->attrs[0]), + notes_attrs = kzalloc(struct_size(notes_attrs, attrs, notes), GFP_KERNEL); if (notes_attrs == NULL) return; diff --git a/kernel/workqueue.c b/kernel/workqueue.c index ca7959be8aaa..c976e2bfbac5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3700,8 +3700,7 @@ apply_wqattrs_prepare(struct workqueue_struct *wq, lockdep_assert_held(&wq_pool_mutex); - ctx = kzalloc(sizeof(*ctx) + nr_node_ids * sizeof(ctx->pwq_tbl[0]), - GFP_KERNEL); + ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL); new_attrs = alloc_workqueue_attrs(GFP_KERNEL); tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); -- cgit v1.2.3-59-g8ed1b