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Summary ======= create_journal() runs only when mode != 'R', so ic->journal stays NULL. Resume treats DIRTY_BITMAP as "journal pages hold a bitmap" and calls rw_journal_sectors() before any journal/mode check: if (ic->sb->flags & cpu_to_le32(SB_FLAG_DIRTY_BITMAP)) { rw_journal_sectors(ic, REQ_OP_READ, ...); /* uses ic->journal[] */ rw_journal_sectors() then passes that NULL page list into dm_io(): io_req.mem.type = DM_IO_PAGE_LIST; io_req.mem.ptr.pl = &ic->journal[pl_index]; /* NULL in mode R */ list_get_page() does *p = pl->page with pl == NULL (KASAN range [0x8-0xf]). DIRTY_BITMAP is set while bitmap mode (B) is active and is cleared on a clean postsuspend. It remains on disk after an unclean stop of mode B (crash / power loss). Reloading that device in recovery mode R is a documented recovery path and hits this bug. Affected ======== - Confirmed on Linux 6.6.144 (da47cbc254661aa66d61ef061485a7080305c4be), KASAN guest - Still present on torvalds/linux master as of 2026-08-17: resume still calls rw_journal_sectors() under DIRTY_BITMAP with no journal / mode-R guard - Files: drivers/md/dm-integrity.c - Config: CONFIG_DM=y, CONFIG_DM_INTEGRITY=y (KASAN for the report) Crash excerpt (from minimized PoC) ================================== KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 234 Comm: repro Not tainted 6.6.144 #15 RIP: 0010:list_get_page+0x7e/0x150 Call Trace: dispatch_io sync_io dm_io rw_journal_sectors dm_integrity_resume dm_table_resume_targets __dm_resume dm_resume dev_suspend ctl_ioctl dm_ctl_ioctl __x64_sys_ioctl Kernel panic - not syncing: Fatal exception Full oops and a self-contained Docker/QEMU reproducer (poc.c + KASAN guest) are available on request. I am happy to test patches or send the reproducer package. Thanks, Yu Junzhe FuzzAnything