exofs: avoid VLA in structures
On the quest to remove all VLAs from the kernel[1] this adjusts several
cases where allocation is made after an array of structures that points
back into the allocation. The allocations are changed to perform
explicit calculations instead of using a Variable Length Array in a
structure.
Additionally, this lets Clang compile this code now, since Clang does
not support VLAIS[2].
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
[2] https://lkml.kernel.org/r/CA+55aFy6h1c3_rP_bXFedsTXzwW+9Q9MfJaW7GUmMBrAp-fJ9A@mail.gmail.com
[keescook@chromium.org: v2]
Link: http://lkml.kernel.org/r/20180418163546.GA45794@beast
Link: http://lkml.kernel.org/r/20180327203904.GA1151@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Boaz Harrosh <ooo@electrozaur.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
index ddbf872..1b8b446 100644
--- a/fs/exofs/ore.c
+++ b/fs/exofs/ore.c
@@ -146,68 +146,82 @@ int _ore_get_io_state(struct ore_layout *layout,
struct ore_io_state **pios)
{
struct ore_io_state *ios;
- struct page **pages;
- struct osd_sg_entry *sgilist;
+ size_t size_ios, size_extra, size_total;
+ void *ios_extra;
+
+ /*
+ * The desired layout looks like this, with the extra_allocation
+ * items pointed at from fields within ios or per_dev:
+
struct __alloc_all_io_state {
struct ore_io_state ios;
struct ore_per_dev_state per_dev[numdevs];
union {
struct osd_sg_entry sglist[sgs_per_dev * numdevs];
struct page *pages[num_par_pages];
- };
- } *_aios;
+ } extra_allocation;
+ } whole_allocation;
- if (likely(sizeof(*_aios) <= PAGE_SIZE)) {
- _aios = kzalloc(sizeof(*_aios), GFP_KERNEL);
- if (unlikely(!_aios)) {
- ORE_DBGMSG("Failed kzalloc bytes=%zd\n",
- sizeof(*_aios));
+ */
+
+ /* This should never happen, so abort early if it ever does. */
+ if (sgs_per_dev && num_par_pages) {
+ ORE_DBGMSG("Tried to use both pages and sglist\n");
+ *pios = NULL;
+ return -EINVAL;
+ }
+
+ if (numdevs > (INT_MAX - sizeof(*ios)) /
+ sizeof(struct ore_per_dev_state))
+ return -ENOMEM;
+ size_ios = sizeof(*ios) + sizeof(struct ore_per_dev_state) * numdevs;
+
+ if (sgs_per_dev * numdevs > INT_MAX / sizeof(struct osd_sg_entry))
+ return -ENOMEM;
+ if (num_par_pages > INT_MAX / sizeof(struct page *))
+ return -ENOMEM;
+ size_extra = max(sizeof(struct osd_sg_entry) * (sgs_per_dev * numdevs),
+ sizeof(struct page *) * num_par_pages);
+
+ size_total = size_ios + size_extra;
+
+ if (likely(size_total <= PAGE_SIZE)) {
+ ios = kzalloc(size_total, GFP_KERNEL);
+ if (unlikely(!ios)) {
+ ORE_DBGMSG("Failed kzalloc bytes=%zd\n", size_total);
*pios = NULL;
return -ENOMEM;
}
- pages = num_par_pages ? _aios->pages : NULL;
- sgilist = sgs_per_dev ? _aios->sglist : NULL;
- ios = &_aios->ios;
+ ios_extra = (char *)ios + size_ios;
} else {
- struct __alloc_small_io_state {
- struct ore_io_state ios;
- struct ore_per_dev_state per_dev[numdevs];
- } *_aio_small;
- union __extra_part {
- struct osd_sg_entry sglist[sgs_per_dev * numdevs];
- struct page *pages[num_par_pages];
- } *extra_part;
-
- _aio_small = kzalloc(sizeof(*_aio_small), GFP_KERNEL);
- if (unlikely(!_aio_small)) {
+ ios = kzalloc(size_ios, GFP_KERNEL);
+ if (unlikely(!ios)) {
ORE_DBGMSG("Failed alloc first part bytes=%zd\n",
- sizeof(*_aio_small));
+ size_ios);
*pios = NULL;
return -ENOMEM;
}
- extra_part = kzalloc(sizeof(*extra_part), GFP_KERNEL);
- if (unlikely(!extra_part)) {
+ ios_extra = kzalloc(size_extra, GFP_KERNEL);
+ if (unlikely(!ios_extra)) {
ORE_DBGMSG("Failed alloc second part bytes=%zd\n",
- sizeof(*extra_part));
- kfree(_aio_small);
+ size_extra);
+ kfree(ios);
*pios = NULL;
return -ENOMEM;
}
- pages = num_par_pages ? extra_part->pages : NULL;
- sgilist = sgs_per_dev ? extra_part->sglist : NULL;
/* In this case the per_dev[0].sgilist holds the pointer to
* be freed
*/
- ios = &_aio_small->ios;
ios->extra_part_alloc = true;
}
- if (pages) {
- ios->parity_pages = pages;
+ if (num_par_pages) {
+ ios->parity_pages = ios_extra;
ios->max_par_pages = num_par_pages;
}
- if (sgilist) {
+ if (sgs_per_dev) {
+ struct osd_sg_entry *sgilist = ios_extra;
unsigned d;
for (d = 0; d < numdevs; ++d) {