Syzkaller reported the following issue: UBSAN: array-index-out-of-bounds in ./include/linux/pagevec.h:74:2 index 255 is out of range for type 'struct folio *[15]' CPU: 1 PID: 12841 Comm: syz-executor402 Not tainted 6.5.0-rc7-syzkaller-g35e2132122ba #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 dump_stack+0x1c/0x28 lib/dump_stack.c:113 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_out_of_bounds+0xfc/0x148 lib/ubsan.c:348 folio_batch_add include/linux/pagevec.h:74 [inline] find_lock_entries+0x8fc/0xd84 mm/filemap.c:2089 truncate_inode_pages_range+0x1b0/0xf74 mm/truncate.c:364 truncate_inode_pages mm/truncate.c:449 [inline] truncate_inode_pages_final+0x90/0xc0 mm/truncate.c:484 ntfs_evict_inode+0x20/0x48 fs/ntfs3/inode.c:1790 evict+0x260/0x68c fs/inode.c:664 iput_final fs/inode.c:1788 [inline] iput+0x734/0x818 fs/inode.c:1814 ntfs_fill_super+0x3648/0x3f90 fs/ntfs3/super.c:1420 get_tree_bdev+0x378/0x570 fs/super.c:1318 ntfs_fs_get_tree+0x28/0x38 fs/ntfs3/super.c:1647 vfs_get_tree+0x90/0x274 fs/super.c:1519 do_new_mount+0x25c/0x8c8 fs/namespace.c:3335 path_mount+0x590/0xe04 fs/namespace.c:3662 do_mount fs/namespace.c:3675 [inline] __do_sys_mount fs/namespace.c:3884 [inline] __se_sys_mount fs/namespace.c:3861 [inline] __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3861 __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155 el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 In folio_batch_add, which contains folios rather than fixed-size pages, there is a chance that the array index will fall outside of bounds. Before adding folios, examine the available space to fix. The patch is tested via syzbot. Reported-by: syzbot+e295147e14b474e4ad70@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?extid=e295147e14b474e4ad70 Signed-off-by: Atul Raut <rauji.raut@xxxxxxxxx> --- include/linux/pagevec.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h index 87cc678adc85..208f9a99889f 100644 --- a/include/linux/pagevec.h +++ b/include/linux/pagevec.h @@ -71,7 +71,9 @@ static inline unsigned int folio_batch_space(struct folio_batch *fbatch) static inline unsigned folio_batch_add(struct folio_batch *fbatch, struct folio *folio) { - fbatch->folios[fbatch->nr++] = folio; + if (folio_batch_space(fbatch)) + fbatch->folios[fbatch->nr++] = folio; + return folio_batch_space(fbatch); } -- 2.34.1
