From 5ad9b4719fc9bc4715c7e19875a962095b0577e7 Mon Sep 17 00:00:00 2001 From: pengfuyuan Date: Tue, 23 May 2023 15:09:55 +0800 Subject: [PATCH] btrfs: fix csum_tree_block page iteration to avoid tripping on -Werror=array-bounds MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When compiling on a MIPS 64-bit machine we get these warnings: In file included from ./arch/mips/include/asm/cacheflush.h:13, from ./include/linux/cacheflush.h:5, from ./include/linux/highmem.h:8, from ./include/linux/bvec.h:10, from ./include/linux/blk_types.h:10, from ./include/linux/blkdev.h:9, from fs/btrfs/disk-io.c:7: fs/btrfs/disk-io.c: In function ‘csum_tree_block’: fs/btrfs/disk-io.c:100:34: error: array subscript 1 is above array bounds of ‘struct page *[1]’ [-Werror=array-bounds] 100 | kaddr = page_address(buf->pages[i]); | ~~~~~~~~~~^~~ ./include/linux/mm.h:2135:48: note: in definition of macro ‘page_address’ 2135 | #define page_address(page) lowmem_page_address(page) | ^~~~ cc1: all warnings being treated as errors We can check if i overflows to solve the problem. However, this doesn't make much sense, since i == 1 and num_pages == 1 doesn't execute the body of the loop. In addition, i < num_pages can also ensure that buf->pages[i] will not cross the boundary. Unfortunately, this doesn't help with the problem observed here: gcc still complains. To fix this add a compile-time condition for the extent buffer page array size limit, which would eventually lead to eliminating the whole for loop. CC: stable@vger.kernel.org # 5.10+ Signed-off-by: pengfuyuan Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 6de6dcf..2b1b227 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -96,7 +96,7 @@ static void csum_tree_block(struct extent_buffer *buf, u8 *result) crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE, first_page_part - BTRFS_CSUM_SIZE); - for (i = 1; i < num_pages; i++) { + for (i = 1; i < num_pages && INLINE_EXTENT_BUFFER_PAGES > 1; i++) { kaddr = page_address(buf->pages[i]); crypto_shash_update(shash, kaddr, PAGE_SIZE); } -- 2.7.4