From: Kees Cook <keescook@xxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxx [2] https://lkml.kernel.org/r/CA+55aFy6h1c3_rP_bXFedsTXzwW+9Q9MfJaW7GUmMBrAp-fJ9A@xxxxxxxxxxxxxx [keescook@xxxxxxxxxxxx: 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@xxxxxxxxxxxx> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Cc: Boaz Harrosh <ooo@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/exofs/ore.c | 82 ++++++++++++++++++++++++------------------ fs/exofs/ore_raid.c | 75 ++++++++++++++++++++++++++++---------- fs/exofs/super.c | 23 +++++------ 3 files changed, 114 insertions(+), 66 deletions(-) diff -puN fs/exofs/ore.c~exofs-avoid-vla-in-structures fs/exofs/ore.c --- a/fs/exofs/ore.c~exofs-avoid-vla-in-structures +++ a/fs/exofs/ore.c @@ -146,68 +146,82 @@ int _ore_get_io_state(struct ore_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; + + */ + + /* 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 (likely(sizeof(*_aios) <= PAGE_SIZE)) { - _aios = kzalloc(sizeof(*_aios), GFP_KERNEL); - if (unlikely(!_aios)) { - ORE_DBGMSG("Failed kzalloc bytes=%zd\n", - sizeof(*_aios)); + 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) { diff -puN fs/exofs/ore_raid.c~exofs-avoid-vla-in-structures fs/exofs/ore_raid.c --- a/fs/exofs/ore_raid.c~exofs-avoid-vla-in-structures +++ a/fs/exofs/ore_raid.c @@ -71,6 +71,11 @@ static int _sp2d_alloc(unsigned pages_in { struct __stripe_pages_2d *sp2d; unsigned data_devs = group_width - parity; + + /* + * Desired allocation layout is, though when larger than PAGE_SIZE, + * each struct __alloc_1p_arrays is separately allocated: + struct _alloc_all_bytes { struct __alloc_stripe_pages_2d { struct __stripe_pages_2d sp2d; @@ -82,55 +87,85 @@ static int _sp2d_alloc(unsigned pages_in char page_is_read[data_devs]; } __a1pa[pages_in_unit]; } *_aab; + struct __alloc_1p_arrays *__a1pa; struct __alloc_1p_arrays *__a1pa_end; - const unsigned sizeof__a1pa = sizeof(_aab->__a1pa[0]); + + */ + + char *__a1pa; + char *__a1pa_end; + + const size_t sizeof_stripe_pages_2d = + sizeof(struct __stripe_pages_2d) + + sizeof(struct __1_page_stripe) * pages_in_unit; + const size_t sizeof__a1pa = + ALIGN(sizeof(struct page *) * (2 * group_width) + data_devs, + sizeof(void *)); + const size_t sizeof__a1pa_arrays = sizeof__a1pa * pages_in_unit; + const size_t alloc_total = sizeof_stripe_pages_2d + + sizeof__a1pa_arrays; + unsigned num_a1pa, alloc_size, i; /* FIXME: check these numbers in ore_verify_layout */ - BUG_ON(sizeof(_aab->__asp2d) > PAGE_SIZE); + BUG_ON(sizeof_stripe_pages_2d > PAGE_SIZE); BUG_ON(sizeof__a1pa > PAGE_SIZE); - if (sizeof(*_aab) > PAGE_SIZE) { - num_a1pa = (PAGE_SIZE - sizeof(_aab->__asp2d)) / sizeof__a1pa; - alloc_size = sizeof(_aab->__asp2d) + sizeof__a1pa * num_a1pa; + /* + * If alloc_total would be larger than PAGE_SIZE, only allocate + * as many a1pa items as would fill the rest of the page, instead + * of the full pages_in_unit count. + */ + if (alloc_total > PAGE_SIZE) { + num_a1pa = (PAGE_SIZE - sizeof_stripe_pages_2d) / sizeof__a1pa; + alloc_size = sizeof_stripe_pages_2d + sizeof__a1pa * num_a1pa; } else { num_a1pa = pages_in_unit; - alloc_size = sizeof(*_aab); + alloc_size = alloc_total; } - _aab = kzalloc(alloc_size, GFP_KERNEL); - if (unlikely(!_aab)) { + *psp2d = sp2d = kzalloc(alloc_size, GFP_KERNEL); + if (unlikely(!sp2d)) { ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size); return -ENOMEM; } + /* From here Just call _sp2d_free */ - sp2d = &_aab->__asp2d.sp2d; - *psp2d = sp2d; /* From here Just call _sp2d_free */ - - __a1pa = _aab->__a1pa; - __a1pa_end = __a1pa + num_a1pa; + /* Find start of a1pa area. */ + __a1pa = (char *)sp2d + sizeof_stripe_pages_2d; + /* Find end of the _allocated_ a1pa area. */ + __a1pa_end = __a1pa + alloc_size; + /* Allocate additionally needed a1pa items in PAGE_SIZE chunks. */ for (i = 0; i < pages_in_unit; ++i) { + struct __1_page_stripe *stripe = &sp2d->_1p_stripes[i]; + if (unlikely(__a1pa >= __a1pa_end)) { num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa, pages_in_unit - i); + alloc_size = sizeof__a1pa * num_a1pa; - __a1pa = kcalloc(num_a1pa, sizeof__a1pa, GFP_KERNEL); + __a1pa = kzalloc(alloc_size, GFP_KERNEL); if (unlikely(!__a1pa)) { ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n", num_a1pa); return -ENOMEM; } - __a1pa_end = __a1pa + num_a1pa; + __a1pa_end = __a1pa + alloc_size; /* First *pages is marked for kfree of the buffer */ - sp2d->_1p_stripes[i].alloc = true; + stripe->alloc = true; } - sp2d->_1p_stripes[i].pages = __a1pa->pages; - sp2d->_1p_stripes[i].scribble = __a1pa->scribble ; - sp2d->_1p_stripes[i].page_is_read = __a1pa->page_is_read; - ++__a1pa; + /* + * Attach all _lp_stripes pointers to the allocation for + * it which was either part of the original PAGE_SIZE + * allocation or the subsequent allocation in this loop. + */ + stripe->pages = (void *)__a1pa; + stripe->scribble = stripe->pages + group_width; + stripe->page_is_read = (char *)stripe->scribble + group_width; + __a1pa += sizeof__a1pa; } sp2d->parity = parity; diff -puN fs/exofs/super.c~exofs-avoid-vla-in-structures fs/exofs/super.c --- a/fs/exofs/super.c~exofs-avoid-vla-in-structures +++ a/fs/exofs/super.c @@ -549,27 +549,26 @@ static int exofs_devs_2_odi(struct exofs static int __alloc_dev_table(struct exofs_sb_info *sbi, unsigned numdevs, struct exofs_dev **peds) { - struct __alloc_ore_devs_and_exofs_devs { - /* Twice bigger table: See exofs_init_comps() and comment at - * exofs_read_lookup_dev_table() - */ - struct ore_dev *oreds[numdevs * 2 - 1]; - struct exofs_dev eds[numdevs]; - } *aoded; + /* Twice bigger table: See exofs_init_comps() and comment at + * exofs_read_lookup_dev_table() + */ + const size_t numores = numdevs * 2 - 1; struct exofs_dev *eds; unsigned i; - aoded = kzalloc(sizeof(*aoded), GFP_KERNEL); - if (unlikely(!aoded)) { + sbi->oc.ods = kzalloc(numores * sizeof(struct ore_dev *) + + numdevs * sizeof(struct exofs_dev), GFP_KERNEL); + if (unlikely(!sbi->oc.ods)) { EXOFS_ERR("ERROR: failed allocating Device array[%d]\n", numdevs); return -ENOMEM; } - sbi->oc.ods = aoded->oreds; - *peds = eds = aoded->eds; + /* Start of allocated struct exofs_dev entries */ + *peds = eds = (void *)sbi->oc.ods[numores]; + /* Initialize pointers into struct exofs_dev */ for (i = 0; i < numdevs; ++i) - aoded->oreds[i] = &eds[i].ored; + sbi->oc.ods[i] = &eds[i].ored; return 0; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
