Hi Liu, [auto build test WARNING on v4.13-rc4] [also build test WARNING on next-20170811] [cannot apply to btrfs/next] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Liu-Bo/Btrfs-fix-out-of-bounds-array-access-while-reading-extent-buffer/20170810-235607 config: x86_64-randconfig-a0-08120433 (attached as .config) compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 All warnings (new ones prefixed by >>): fs//btrfs/extent_io.c: In function 'read_extent_buffer': >> fs//btrfs/extent_io.c:5419: warning: unused variable 'num_pages' vim +/num_pages +5419 fs//btrfs/extent_io.c 5407 5408 void read_extent_buffer(struct extent_buffer *eb, void *dstv, 5409 unsigned long start, 5410 unsigned long len) 5411 { 5412 size_t cur; 5413 size_t offset; 5414 struct page *page; 5415 char *kaddr; 5416 char *dst = (char *)dstv; 5417 size_t start_offset = eb->start & ((u64)PAGE_SIZE - 1); 5418 unsigned long i = (start_offset + start) >> PAGE_SHIFT; > 5419 unsigned long num_pages = num_extent_pages(eb->start, eb->len); 5420 5421 if (start + len > eb->len) { 5422 WARN(1, KERN_ERR "btrfs bad mapping eb start %llu len %lu, wanted %lu %lu\n", 5423 eb->start, eb->len, start, len); 5424 memset(dst, 0, len); 5425 return; 5426 } 5427 5428 offset = (start_offset + start) & (PAGE_SIZE - 1); 5429 5430 while (len > 0) { 5431 ASSERT(i < num_pages); 5432 page = eb->pages[i]; 5433 5434 cur = min(len, (PAGE_SIZE - offset)); 5435 kaddr = page_address(page); 5436 memcpy(dst, kaddr + offset, cur); 5437 5438 dst += cur; 5439 len -= cur; 5440 offset = 0; 5441 i++; 5442 } 5443 } 5444 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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