22.11.2022 06:29, Matthew Wilcox пишет:
On Fri, Nov 18, 2022 at 03:20:32PM +0300, Dan Carpenter wrote:Hello Ananda, The patch 9097e28c25c8: "mm: add zblock - new allocator for use via zpool API" from Nov 4, 2022, leads to the following Smatch static checker warning: mm/zblock.c:341 zblock_alloc() error: buffer overflow 'block_desc' 29 <= 29 (assuming for loop doesn't break) mm/zblock.c:165 cache_insert_block() error: uninitialized symbol 'min_index'. mm/zblock.c:412 zblock_reclaim_block() warn: always true condition '(block_type >= 0) => (0-u64max >= 0)' mm/zblock.c 297 static int zblock_alloc(struct zblock_pool *pool, size_t size, gfp_t gfp, 298 unsigned long *handle) 299 { 300 unsigned int block_type, slot; 301 struct zblock_block *block; 302 struct block_list *list; 303 304 if (!size) 305 return -EINVAL; 306 307 if (size > PAGE_SIZE) 308 return -ENOSPC; 309 310 /* find basic block type with suitable slot size */ 311 for (block_type = 0; block_type < ARRAY_SIZE(block_desc); block_type++) { 312 if (size <= block_desc[block_type].slot_size) 313 break; 314 } "size" is always <= PAGE_SIZE. Is PAGE_SIZE always 4k? If so then this code is fine. Smatch is bad at handling arrays.PAGE_SIZE is 8kB on SPARC/Alpha. It can be 64kB on PPC and ARM. It can even be 256kB on one of the weirdo architectures (but, honestly, it's OK if that breaks; it's not well-tested)..
The block_desc table uses fractions of PAGE_SIZE, so with larger PAGE_SIZE, the size of slots will also increase. Should work fine with a page size of 8, 64, 256k.
